Main Menu & Tileset Tools Menu Changes

Added a new menu item to main menu - Load Recent Projects;
Tileset Tools are now only enabled when a tileset item is selected in
Scene Hierarchy.
merge
Merge branch 'master' of https://github.com/Whitebeard86/Gibbo2D

Conflicts:
	Gibbo.Editor.Model/obj/Release/Gibbo.Editor.Model.csproj.GenerateResource.Cache
	Gibbo.Editor.WPF/bin/Release/Gibbo.Editor.WPF.application
	Gibbo.Editor.WPF/bin/Release/Gibbo.Editor.WPF.exe
	Gibbo.Editor.WPF/bin/Release/Gibbo.Editor.WPF.exe.manifest
	Gibbo.Editor.WPF/bin/Release/Gibbo.Editor.WPF.pdb
	Gibbo.Editor.WPF/bin/Release/Gibbo.Editor.WPF.vshost.application
	Gibbo.Editor.WPF/bin/Release/Gibbo.Editor.WPF.vshost.exe.manifest
	Gibbo.Editor.WPF/obj/Release/Gibbo.Editor.WPF.application
	Gibbo.Editor.WPF/obj/Release/Gibbo.Editor.WPF.csproj.GenerateResource.Cache
	Gibbo.Editor.WPF/obj/Release/Gibbo.Editor.WPF.csprojResolveAssemblyReference.cache
	Gibbo.Editor.WPF/obj/Release/Gibbo.Editor.WPF.exe
	Gibbo.Editor.WPF/obj/Release/Gibbo.Editor.WPF.exe.manifest
	Gibbo.Editor.WPF/obj/Release/Gibbo.Editor.WPF.pdb
Merge pull request #4 from Whitebeard86/master

Update