make gl3 text renderer handle multilines (\n) proper
implement font (measuretext) so it should be giving back good sizes

of width and height, including handling newlines now.
attempt to finally fix measureText

unfortunately multilined edit boxes act funny, as do textboxen with text
spanning past the end of the box. More specifically, the cursor acts
strange with it. This needs definite improvement, but I'm not sure where
to start..
re-enable scissoring, fix SDL 2 input so it now works to write chars