Fixed (or suppressed) all compiler warnings

I got bored :)

libs: warnings merely suppressed
sb: 
- fixed warnings properly where possible
- some undeclared selectors fixed using protocol so the warning will resurface if selector in question is renamed
- suppress loadNibNamed: deprecation warnings (added a FIXME comment)
- removed framework search paths from target "SpriteBuilder" because they generated "directory not found" warnings. The SpriteBuilder build settings already had the correct framework search path set: "libs".

This can be closed:
https://github.com/apportable/SpriteBuilder/issues/90