Don't create ".orig" files when invoking "arc patch" command for SVN working copies

See https://secure.phabricator.com/T6424
Add support for parsing diffs, created by PhpStorm

See https://secure.phabricator.com/T4698
Support files in "svn:externals" property in SVN 1.6+ working copies

Summary:
These changes allow detection of files, that come from folder's "svn:externals" property. Before only folders were properly detected.

Fixes T6447

Test Plan:
# create 2 svn repositories (internally these can be 2 folders on same SVN server of course)
# configure 2nd folder to include one folder and one file (try binary file, like "favicon.ico") via "svn:externals" property
# checkout 2nd folder
# try running `arc diff`

Before this would result in UTF-8 encoding error on binary file that came from "svn:externals". Now file will be properly skipped.

Reviewers: #blessed_reviewers

Subscribers: epriestley

Maniphest Tasks: T6447

Differential Revision: https://secure.phabricator.com/D10772
Answering "N" to external change prompt will include externals in created diff

See https://secure.phabricator.com/T6446
Automatically populate "Jira Issues" field from commit message

See https://secure.phabricator.com/T6451
Enhance "arc diff" command with "--cl" option for SVN changelist selection

See https://secure.phabricator.com/T6437