the RPG namespace requires some refactoring

[niokasgami]

As you can see there's a Common data interface namespace named 'RPG' who hold all the reused data structure in the engine.

Kino designed it in the past just a big namespace to hold everything although it is very messy and has a lot of duplicates.
So I am suggesting that we refactor the RPG namespace to be cleaner and easier to search through.

I am open to conversation about how we could improve it.

My overall idea was :

RPG.DATA would be used for all the DATA folder
while RPG.EVENTS would be used for the events related interfaces.
and finally RPG.COMMON would be for the general interfaces likes (Musics etc)

I am open to idea though

[niokasgami]

@masked-rpgmaker did the refactoring !