INPC initial commit

INPC: duplicate NotifyChangedOptions attribute error added

INPC refactoring
Merge branch 'INPC' of github.com:Stitchous/nemerle

Conflicts:
	snippets/Nemerle.WPF/Nemerle.WPF/NotifyPropertyChanged.n
	snippets/Nemerle.WPF/Test/NotifyPropertyChangedTests.n