Create a maven like project structure for java development. Make it OSGi compliant. Generate the flatbuffers code for testing (example).

Java developer are mostly comfortable with maven project structure. One one the main concept behind maven is convention. If you follow the maven project convention then your development team will get more effective as they now this project structure and can easily find the production code versus the test code.
 In this pull request I have structured the java project around 2 main parts:
  * the `flatbuffers` project. This project is the api / lib project and contains the test code structure + an example of code generation for testing. This avoid to commit generated code. Pre-configure JUnit for test driven development and make this project OSGi compliant.
  * the `jmh` project. This project aims to provide a placeholder for micro-benchmarking. JMH is a 'de facto' standard for micro benchmarking you can find more details here: http://openjdk.java.net/projects/code-tools/jmh/

For now I didn't move the JavaTest class but it could be a next step with a migration to the JUnit framework.
The only impacts are the move of the class and the project structure => no code change.

Share warning and two methods

Added helpers to access objects while creating the flatbuffer.

More bit fields patches

More descriptive name, show that it's really just a temporary object.

Close #3892

Instead we need NONE (0) and ANY (all orred values), if the user didn't
already defined them

We just need to pass it to DEFINE_BITMASK_OPERATORS macro

Define bit mask operators for scoped enums bitfields

MSVC doesn't allow alignment on function params.

Close #3887

shared method that exits early if everything is generated

MSVC doesn't allow alignment on function params. This prevents the copy and thus avoids this issue https://msdn.microsoft.com/en-us/library/373ak2y1.aspx

Handle \u-escaped surrogate pairs correctly in IDL parser

Change-Id: I64307ccd0a6f23a7c3860d602813e637415e7c91

Change-Id: Ie7cc268a8823aec1d06c8b7cbef54068d832de3a

Remove Remaining FBB#createString Allocation

Also removed some trailing whitespace.

Change-Id: I40bf4f776ca4d467b7ee6f2c9a7500c13700f9d5

Bug: https://github.com/google/flatbuffers/issues/3872
Change-Id: I5d551168e9bc925e867e5e4ddf5d809418fd44eb
Tested: on Linux.

eliminating the last remaining allocation in string creation

Use the build output flatc to compile test schemas by default.

Fix undefined behavior when CheckBitsFit left-shifts 64-bit value by 64 bits

Bug: 28762769
Change-Id: Iec370482f67c4585e97dd5175c1a4258ddba47fe
Tested: on Linux.

Fixed Library Location in CppUsage.md

Fixed Library Location 
"https://github.com/google/flatbuffers/tree/master/include/flatbuffers"
in CppUsage.md

GetObject and GetMutableObject are similar to GetRoot and GetMutableRoot,
and can be useful when wanting to access data that has just been created.
Unfortunately there is a danger in using these methods, as it is possible
that the buffer reallocates which will invalidate the pointers.

Fix CreateString with already-encoded string or bytearray in Python 2.7.

Fix for #3853