Fix FormatException in Class Diagram addin.

Visual Studio class diagrams do not store the Collapsed xml attribute when the item is not collapsed.
Fixed SearchAndReplaceBinding.Detach
Allow enter key when editing standard file headers.
Fix blank package summary in Manage Packages dialog packages list.

Display NuGet package description if the summary is missing.
Fix progress bar when running a search in the background.
Fix blank summary in NuGet package license accept dialog.

Use description if the package summary is missing.
Fix index out of range exception in Package Sources option panel.

Disable move buttons if no package source selected.
Fix context actions popup disappearing when clicking the SharpDevelop title bar.
ChangeMarkerMargin: Horizontally align diff popup with the text view
fix http://community.sharpdevelop.net/forums/p/16476/44890.aspx
Fix NuGet package id not displayed in logging output.
AvalonEdit IME: Fix crash on threadMgr.SetFocus(null); in 64-bit process.
Fix disabled package sources being used in Manage Packages dialog.

Selecting All in the package source list was searching across all package
sources including disabled ones.
Show package sources drop down in updated packages tab.

Allow user to choose which package source when looking for updated packages.
Remove All from package source combo box when only one source.

Disabled package sources were being counted when deciding whether to add All
to the combo box in the Manage Packages dialog.
Always show package sources in Available and Updates tab.

Do not hide the package sources combo box in the Manage Packages dialog
when only on package source is defined.
Allow missing projects to be removed from solution.

Remove menu item is now enabled for a missing project.
Fix highlighting colours unavailable for Ruby and Python.

Upgrade Ruby and Python syntax highlighting definitions to
version 2.0 so all named highlighting colours can be modified
in Tools | Options | Highlighting
Fix version number of HTML clipboard.

Version 1.0 does not exist: http://blogs.msdn.com/b/oldnewthing/archive/2013/01/18/10386079.aspx
Document that git must be available on the PATH