* Add ruby 2.6 gem build for linux

* Add docker hub organization

* Add ruby2.6 in cross compile targets

* Fix tests

* Check mac version

* No need to install php in preparation for mac

* Add ruby 2.6 test

* Fix broken tests

* Fix compatibility test

* Fix bundler version

* Use new docker image

* Fix broken test

* Use new docker image in ruby26 test

* Install ruby for mac

Clean up unnecessary compile warning with GCC

The -Wno-writable-strings warning flag is Clang-specific. GCC's
equivalent is -Wno-write-strings, which Clang also supports as a
synonym. So, -Wno-write strings is more compatible and there is no need
to specify both.

https://clang.llvm.org/docs/DiagnosticsReference.html#wwrite-strings
https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html

* Fix Any json encoding/decoding in php

* Fix comments

Enable the ignore_unknown_field option in the Ruby unmarshal options

Use NoLocalStrtod for international compliance

This adds the ability for the MRI Ruby library to optionally pass in a
ignore_unknown_fields option when decoding JSON. The functionality was
added upstream in upb, this change exposes that option.

Down-integrate internal changes to github.

Add conformance test for allow_alias with lower_case enums

Lower the severity of lower-case ruby enum to warning. Add conformance test for allow_alias with lower_case enums

Recieved errors pasing json files with decimal floats from European colleagues

* Rebuild python docker image

* Update docker image

* Change call to build_and_run_docker.sh

* Set up python tests for different versions

* Fix comments

Exclude command_line_interface_unittest.cc in MSVC build

* Fix benchmark to use docker image on kokoro

* Deleted pure php benchmark and fix long time benchmark

Removed Kokoro config for 64-bit Linux

This Kokoro configuration is no longer being used and the build.sh
script does not work anymore, so let's delete this configuration.

* Inherit from message instead of implement

When regestering class (implmenets other class) during MINIT, zend_class_implements
would call zend_class_entry->interface_gets_implemented(). In PHP-7.3 interface_gets_implemented shares the same location with create_object.
However, during MINIT, the global object storeage hasn't been initialized. And thus, caused segment fault in php 7.3.

* Use zend_string_init where interned string may be the value.
zend_string_dup will keep using the existing interned string.
In php 7.3, interned string cannot be destroyed from user's code.

* Uncommment debug code

* Use latest phpunit for each php versions

* Revert change in Dockerfile

* Update php test to use the new docker image

* Update composer

* Change docker organization

* Update phpunit

* Debug phpunit

* Store phpunit into bin dir in docker image

* Install valgrind to docker

* Fix compatibility test

* Remove generated_service_test from compatibility c extension test

* Update 32bit php test to the new docker image

* Install bison

* Fix build.sh

* Fix DOCKERIMAGE_PREFIX

* Fix basename

* Add comment to build_and_run_docker2.sh

* Remove commented code

* Fix comments

Some protos have enum values of "FOO" and "Foo", which the ObjC generation
then makes into the same thing. Just skip generating the enum element for
the duplicate as it would be a compile error because of the name collision.

The descriptors are still generated to support reflection and TextFormat
more completely.

Don't look up the TextFormat for the value as aliases can trip that
up, instead check the TextFormat names directly and then fetch the
value.

* Down-integrate internal changes

* Update generated code for php, objc and csharp.

* Add missing dependency in conformance_php

Replace update_version shell script with a python script

Replace update_version shell script with a python script, which is much better at handling XML rewrite. Update the PHP version too. As part of rewrite, some XML file format will change a little, but the semantics is still the same so it should be okay.