gio: update MSBuild csproj file to account for recent changes
generator: fix AssemblyName in MSBuild csproj

To be the same as what is generated via Makefiles.
generator: add reference to System.Core in the MSBuild csproj

Extension methods (such as the one we have in XmlElementExtensions.cs)
need to link to System.Runtime.CompilerServices.ExtensionAttribute
class in order to compile. In .NET 3.5, this was part of System.Core
(not mscorlib like in .NET 4.5) [1], so we need to link to it in order
to compile via MSBuild.

[1] http://msdn.microsoft.com/en-us/library/system.runtime.compilerservices.extensionattribute%28v=vs.90%29.aspx
gdk: enable Unsafe in MSBuild
gtk: reference Cairo in MSBuild csproj
glib: include recent files committed in master to the MSBuild csproj
Merge pull request #83 from knocte/msbuild_tweaks

Various tweaks and updates to the .csproj files