* Bump target frameworks from netcoreapp1.0 to netcoreapp2.2.
Move global.json up to root of repo, change SDK ver to 2.2.100
Change .net core sdk in dockerfile for kokoro to ver 2.2.100

* Re-add curl install

* Change all exe target to 2.1

* Fix incorrect versions in global.json and Dockerfile

* Downgrade version to 2.1 to match exe targets

* introduce separate testing Dockerfile for C#

* revert changes to the shared Dockerfile

* use netcoreapp2.1 for C# conformance tests

* use language specific dockerfile for testing C#

* Edit compatibility tests script to use parameters instead of file copies

* install dotnet SDK on windows before running the tests

* update csharp_EXTRA_DIST

* Improve C# serialization performance of repeated fields for primitives.

* Changes based on feedback.

* Change compatibility tests to chec float, bool and double are fixed

* Changes based on feedback.

* In the compute methods use the newly created constants

Recently dependency to error_prone_annotations was added to the code,
but only Maven build tool chain was updated.

Closes #5795.

* Fix ruby continuous tests

* Fix compatibility test

* Add link to continuous test badges

* Add badge for dist_install

* Add a new test for verifying that the dist package can be installed.

* Some fixes to make the code work in google3.

* Removed plugin.h.

* Some more fixes to be namespace-independent.

* More fixes for namespace independence.

* A few final fixes.

* Another fix (hide ToUpper from Copybara).

* Fix for charp_unittest.

This change introduces a CriticalSectionLock class as a lightweight replacement for std::mutex on Windows platforms. std::mutex does not work on Windows XP SP2 with the latest VC++ libraries, because it utilizes the Concurrency Runtime that uses ::GetLogicalProcessorInformation which is only supported on Windows XP SP3 and above.

This reverts commit 37581380.

* Down integrate to github

Merge 3.7.x to master

Replaced shortn URL with intended URL.

* Revert "Revert "Fix Ruby module name generation when the ruby_package option is used (#5735)""

This reverts commit bb211e85.

* add new files to Makefile.am

* add frozen checks

* Use rb_check_frozen

* Correct assertion on frozen error message

The second argument for the method assert_raise is the message
to show when the assertion fails. It does not check the error
object's message.
Add an additional assertion that does check the error's message.

* do frozen check first

* example with extra enum method

* update expected test output

* slight simplification

* add test for generated enum helpers

* move const helpers to c extension

* more explicit test

* more explicit test

* indent

* add foo test

* add check for _const suffix

Updating Iterators to be compatible with C++17 in MSVC

* Update version number to 3.7.0

* Add php/releash.sh to Makefile.am

* Make cpp_distcheck exit on fail

Revert "Fix Ruby module name generation when the ruby_package option is used"

This reverts commit 9638dcc3.

* fix module name generation and add tests

* fix existing tests

* support both package name styles

* add check for overflow

* de-nestify

* break long lines

* let repeated fields push arrays

* add varargs push

* better test

* Fix construction of messages using the C++ Python implementation when a map field is passed from one message to another.

* Add a test on message map field construction

* python 3 support

* review comments

* add test

* Collapse code into one

Added Optional GRPC library to third party docs

down integration from internal

Cherry-pick fixing for mac tests after kokoro updates 

* fix macos build by changing xcode version

* add comments

* fix benchmark build for mac

* fix for gem option and install npm

* add test for node and npm

* fix node

* fix for node

* another attempts to fix node

* another attempts

* clean up

* Fix #5513

* Added tests for invalid lengths when reading strings and bytes.
Added test for reading tags with invalid wire types in unknown field set.
Changed invalid length check in ReadString to match the one in ReadBytes