Parser: Make value parsing functions return the value and not use a parameter
Parser: Make value parsing functions return the value and not use a parameter

Also added parse_*_value functions for literals and identifier, to give the
actual value not wrapped in ViviCodeValueSomething

freedesktop-unofficial-mirror/swfdec__swfdec,mltframework/swfdec,freedesktop-unofficial-mirror/swfdec__swfdec,freedesktop-unofficial-mirror/swfdec__swfdec,mltframework/swfdec