Official Library File Format Restictions

[Orion Pobursky]

More edits:

I renamed the document to LDraw.org Official Library Specifications
I read through the entire document and reformatted/rewrite for clarity
I added the sticker shortcut stuff that was previously discussed in private forum
I added more of flexible parts

I'm sure I forgot some suggestions. Please read and comment. 

I think we're in the end game. Let's knock this out.