Source code checked in, #5760

Updated Extensions to re-use code in Count and FirstOrDefault as suggested by Corey Kosak. A wider attempt at reducing program space usage. Added a new project (so it builds to its own library to save space if you don't need it) for Prebuilt Delegates again suggested or inspired by comments from Corey Kosak. These will help keep end-code cleaner by moving the casting operations out a level.