Get data about available versions from config file.
Allow to create archive with difference between 2 revisions

#1361
Allow to create archive with revision filter from Menu

#1361
Archive revision's checkbox shouldn't be checked if there is only one revision
Added link to coding guide wiki page
rearranged layout
Merge pull request #1915 from feinstaub/minor_fixes

comments added/removed for MenuCommands
Uncheck Revision path checkbox or revision diff checkbox when checking the other one.

Hide diff commit summary control
Handle new descriptions of detached head introduced in git 1.8.3

see git gc8183cd builtin/branch.c

There are 4 types in total:
(no branch, rebasing %s)
(no branch, bisect started on %s)
(detached from %s)
(no branch)

Conflicts:
	GitUI/FormBrowse.cs
	GitUI/FormPull.cs
Selecting items in FormCommit improved, should update diff view only when needed
restore last selected items on reload

(cherry picked from commit 28ecafa4e995d195b7784f93078d13e6868b2e83)

Conflicts:
	GitUI/CommandsDialogs/FormCommit.cs
Update ref to _currentFilesList after unstage all
Keep selection on last staged/unstaged file
- Removed sort on selected revision

- Change commit summary to a small one
Fixed selection when staging/unstaging selected lines.
Check if focus is where it was initially. Fixes #1899.
move user manual handling out of UI
move open in default browser functionality out of UI
Merge branch 'pr/n1918_mexx'
Corrected URIs