This performance optimization allows to skip reflection (in the is() method) when the message has been already unpacked once

* Modify how end tags are encounted in merge code (compiler)

* Modify how end tags are encounted in merge code (generated)

* Modify how end tags are encounted in merge code (library)

* Regenerate generated code through generate_descriptor_proto.sh

I tried finding an active repo on github with no success.  The only ProtoSharp I found wasn't related to PB at all.

* add more descriptive error messages to init methods

* add type errors test to Makefile.am

Document why no enum_extensibility is needed for Swift.

It already exists for wire and json formats

Fix below issue:
src/Makefile.am:210: warning: whitespace following trailing backslash
Signed-off-by: Xiang Dai <764524258@qq.com>

libprotobuf being targed before libprotoc was causing Visual Studio to fail in linking protoc.

* Fix GetErrno() to be const noexcept

* Removed noexcept

* Use set -ex
* Use -std=c++14 so -latomic can be found

* Fix python release build.
* Separate config.sh by platform
* Use KOKORO_JOR_NAME to determine the BUILD_COMMIT.
* Use -std=c++14 on MacOS so -latomic can be used.

The draconian heapcheck turns up memory leaks outside our control, such
as ones in libc and in the heapchecker itself. I think for an automated
test it makes more sense for us to use the "strict" heapcheck, since
that already passes and should only report leaks that are within our
control.

Updated googletest submodule to the most recent upstream commit

Update guava version to 26

Update more files in update_version.py

* Fix more issues for reference values

* Revert change in gdb test

* Add more tests

* Fix protoc release

* Update Dockerfile to include libatomic

* Add TC malloc kokoro test

* Update tcmalloc test

* Fix empty FieldMask json encoding/decoding

* Add failed test to python's conformance failure list

* Fix c extension doesn' allow message reference in array

* Fix array constructor handling reference of array.

* Change test name

Add proto3 to solidity link in third_party.md

* Fixed compile warnings for PHP extension.

* Fixed some compile errors on PHP <7 and with TSR enabled.

* One more fix for TSRM builds.

Revert "doc: apply consistent indentation to Any examples"

This reverts commit b3367aee.

* Fix Any json encoding/decoding for ruby.

* Revert unnecessary changes

* Fix field mask for php in json

* Update byte size

pb3-gen-sol is a proto3 to solidity library generator that supports proto3 native types and uses field option for solidity native types. Both the message and generated code are more efficient than other solutions. It also includes a library to decode protobuf wireformat.