C++: Fixed generated header file cannot be compiled when the type of key is enum class

Fixes issue #348: C# vector of enums doesn't compile

Fixes a bug where the logic to determine when to use a C# enum flags
both enums and vectors of enums.  This causes the C# generator to
generate code that doesn't compile for tables that contain vectors of
enums.

The fix also consolidates type generation functions a bit and adds
some additional casting functions for clarity.

Fix projectfile (VisualStudio, XCode) for development

Tested:
Verified it's possible to build generated headers on Linux for Android.

Change-Id: I82249a252cb851b978a177f4a4b92b527cc2bfd9

Also, added missing build scripts for flatc on Windows and fixed
numerous issues in the flatbuffers/android/jni/include.mk makefile.

Tested:
Verified dependent project (motive) can generate flatbuffers headers
with these changes on Android.

Bug: 25780616

Change-Id: I73f0dec8f7a6a7eb4e71951a8f1cd3e0d343a9ff

flatbuffers/cmake: move build_flatbuffers to a standalone file

Add support for PHP code.

C# Unity (.NET 3.5) can't cast enum default value.

So that it could be included from both flatbuffers CMakeLists.txt and
FindFlatBuffers.cmake.

Change-Id: Ie16a879beef9367cd6fd9b2d2157044841a7cdbc

* codegen for all basic features: WIP (probably implemented all basic feature)
* JSON parsing: NO
* Simple mutation: NO
* Reflection: NO
* Buffer verifier: NO (will be add later)
* Testing: basic: Yes
* Testing: fuzz: Yes
* Performance: Not bad
* Platform: Supported Linux, OS X, Windows (has 32bit integer limitation)
* Engine Unity: No

flatc --php monster_test.fbs

  <?php
  //include neccessary files.
  $fbb = new Google\FlatBuffers\FlatBufferBuilder(1);
  $str = $fbb->createString("monster");
  \MyGame\Example\Monster::startMonster($fbb);
  \MyGame\Example\Monster::addHp($fbb, 80);
  \MyGame\Example\Monster::addName($fbb, $str);
  $mon = \MyGame\Example\Monster::endMonster($fbb);
  $fbb->finish($mon);
  echo $fbb->sizedByteArray();

PHP 5.4 higher

Currently, we do not register this library to packagist as still experimental and versioning problem.
If you intended to use flatbuffers with composer. add repostiories section to composer.json like below.

  "repositories": [{
    "type": "vcs",
    "url": "https://github.com/google/flatbuffers"
  }],

 and just put google/flatbuffers.

  "require": {
    "google/flatbuffers": "*"
  }

* PHP's integer is platform dependant. we strongly recommend use 64bit machine
  and don't use uint, ulong types as prevent overflow issue.
  ref: http://php.net/manual/en/language.types.integer.php

* php don't support float type. floating point numbers are always parsed as double precision internally.
  ref: http://php.net/manual/en/language.types.float.php

* ByteBuffer is little bit slow implemnentation due to many chr/ord function calls. Especially encoding objects.
  This is expected performance as PHP5 has parsing arguments overhead. probably we'll add C-extension.

Basically, PHP implementation respects Java and C# implementation.

Note: ByteBuffer and FlatBuffersBuilder class are not intended to use other purposes.
      we may change internal API foreseeable future.

PSR-2, PSR-4 standards.

Implemented simple assertion class (respect JavaScript testcase implementation) as we prefer small code base.
this also keeps CI iteration speed.

we'll choose phpunit or something when the test cases grown.

```
namespace MyGame;

enum CommandType : byte {
	None = 0,
}

table Command {
	id:int;
	type:CommandType;
}
```

then generate c# files. it'll output compile error like these.

```
Assets/MyGame/Command.cs(18,39): error CS1041: Identifier expected
Assets/MyGame/Command.cs(18,39): error CS1737: Optional parameter cannot precede required parameters

16:   public static Offset<Command> CreateCommand(FlatBufferBuilder builder,
17:   int id = 0,
18:   CommandType type = (CommandType)0) {
```

Go: Improve Builder user interface.

Python: Improve Builder user interface.

This allows you to query the generated target for those properties
later, so dependent modules can refer to the directories to, for example,
add them to the include_directories.

Change-Id: I7a6bd34c5c1d08e2ea69b5ad845223297cad1159

This function is designed to be called by projects that use FlatBuffers.
It takes a list of FlatBuffers schemas and a list of schema include
directories, and generates build rules to create generated headers
and/or binary schemas for those files, as well as optionally copying
all of the text schemas into a directory for your use (for example if
you need to parse text schemas within your app).

See function comments for more details.

Change-Id: I181684b916e91d965e14849d8f83ec2c83e9a4a4

local-source-file-path does not expand to correct file paths in
some circumstances so some users override it.  Therefore
flatbuffers_header_build_rules has been modified to generate rules
that expand LOCAL_SRC_FILES values with flatbuffers_header_build_rules.

Also, this overrides local-source-file-path to allow nest projects
to build when NDK_OUT is set.

Tested:
Verified a dependent project continues to build.

Bug: 25673744
Change-Id: Ic90186fe96d6e4533f9f3b7ca9ef78084de08a7e

When $(MAKE) is expanded via a macro "make" doesn't know whether
$(MAKE) refers to an instance of the make app and therefore doesn't
pass job server arguments down.  This change adds the + prefix to the
command in the receipe in order to indicate $(MAKE) is another instance of
make.

Tested:
Verified flatc builds in parallel from Android builds.

Change-Id: I9f2f4f9680b818fdda7420a75a8bfa995b4644db

+ Add state to the Builder object to track if we are inside a table,
  and if we are finished building the buffer.
+ Use this data to check that a buffer is being built correctly.
+ Raise an exception if a buffer is not being built correctly.
+ Test that the exceptions happen as expected.

Based on d236dea1.

+ Add state to the Builder object to track if we are inside a table,
  and if we are finished building the buffer.
+ Use this data to check that a buffer is being built correctly.
+ Panic if a buffer is not being built correctly.
+ Test that the panics happen as expected.

Based on d236dea1.

(C#) Add ByteBuffer property to Table

Change-Id: I607f5f33b609c47fe32342f5e9d066f61f5546cd

Don't hide function parameter

Change-Id: Ib5234a97a863be08c3bb0f9329204bc3a7effccb

Also simplified the code and made it faster.

Change-Id: I1d83b1165a4a9a4380d1bfb5538769c012d2d367
Tested: on Linux.

Change-Id: Idac375b22aa9beaba162084cc3396f5536a4e721
Tested: on Linux.

Change-Id: I82a392bd262b13e978df748bc54b7ac43aec1e15
Tested: on Linux.

* Added the ability to create a build target for generated headers.
* Made it possible for generated header targets to depend upon each
  other or arbitrary build targets.

Tested:
Verified some pretty complex libraries with numerous flatbuffer schema
dependencies build using this macro on Linux with the NDK.
Bug: 25188384

Change-Id: I846855a50808e58c34cdf7086e93e7ea0df69e0d

fix comment generation of struct

Change-Id: I7c04d934bfacd4aeaa2ba476b934dd3a62d4fc0e
Tested: on Linux.

Change-Id: Ie19af91ec5bf0b65297cba58c124bceaa58fd73e