Implement simple text wrapping for PPGe/MsgDialog

Probably kept it too simple, but it does the trick at least for Stick Man Rescue, which had the problem.  Maybe should apply other places, like save text descriptions...

The other thing it needs is scrolling.  I figure it's easy to handle `IsButtonPressed(CTRL_UP)` etc. in `DisplayMessage()`, so then what's left is possibly drawing a scrollbar (or some form of UI indication like an arrow), and cropping the text... but I'm not sure the right way to do that.

-[Unknown]