Submodule GitExtensionsDoc updated

Submodule GitExtensionsDoc:
    > a120c4e - Fix incomplete sentence.
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' of git://github.com/gitextensions/gitextensions
Merge branch 'master' of git://github.com/gitextensions/gitextensions
Merge branch 'master' of git://github.com/gitextensions/gitextensions
Merge branch 'master' of git://github.com/gitextensions/gitextensions
Merge branch 'master' of https://github.com/gitextensions/gitextensions
Merge branch 'master' of git://github.com/vbjay/gitextensions
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Add submodule fetch option to BackgroundFetch plugin
Add Fetch All Submodules sample script
Support VS2013 build
Resized FormDeleteBranch and updated localization

Change-Id: I015d514661fcc8d0ae17c5d6746155832f4ad5b6
Added ProxySwitcher localization and German translation

Change-Id: I28d5dfd7962e672f7ff7bc83b0b7121ea7c113c5
Enlarged FormCheckoutRevision and updated localization

Change-Id: I335bced964257e8518b2dd4af4776bd6988e52da
Updated German translation for changed English strings removing unfinished entries and OldSource

Change-Id: I8dca770b8d0560c20590aaaa4d45fdf414ea7b75
Create branch/tag command in VS fixed. Closes #2117
Installer fixed.

ChangeLog updated. Closes #2119