Add support for parsing diffs, created by PhpStorm

See https://secure.phabricator.com/T4698
Don't create ".orig" files when invoking "arc patch" command for SVN working copies

See https://secure.phabricator.com/T6424
Answering "N" to external change prompt will include externals in created diff

See https://secure.phabricator.com/T6446
Support files in "svn:externals" property in SVN 1.6+ working copies

See https://secure.phabricator.com/T6447
For "arc diff" show files, included in revision in message template
Enhance Arcanist diff/export workflows with "--cl" option for SVN changelist selection

See https://secure.phabricator.com/T6437
Merge branches 'T4698-phpstorm-patch-support', 'T6424-no-orig-files-on-svn-patching', 'T6437-svn-changelist-support' and 'show-included-changes-in-message-template'

* T4698-phpstorm-patch-support:
  Add support for parsing diffs, created by PhpStorm

* T6424-no-orig-files-on-svn-patching:
  Don't create ".orig" files when invoking "arc patch" command for SVN working copies

* T6437-svn-changelist-support:
  Enhance Arcanist diff/export workflows with "--cl" option for SVN changelist selection

* show-included-changes-in-message-template:
  For "arc diff" show files, included in revision in message template
Merge branches 'T6446-svn-external-in-patches' and 'T6447-files-in-svn-externals'

* T6446-svn-external-in-patches:
  Answering "N" to external change prompt will include externals in created diff

* T6447-files-in-svn-externals:
  Support files in "svn:externals" property in SVN 1.6+ working copies

Conflicts:
	src/repository/api/ArcanistSubversionAPI.php