Document how GameMaker batches by default when drawing and what causes batch breaks

[YYBartT]

GameMaker batches draw commands by default, though the manual doesn't mention this at all.

• Explain the basics of this under the Object Editor > Events > Draw Events page.
• Add a page on batching and list the GM functions that break the batch.
• Add a note to the page of all functions that break the batch, "This function breaks the draw batch. See this page for more info".