Bitmap::stretchBlt handles that now

Code mostly taken from the implementation in Bitmap::drawText

…rship of the surface, and provide an option to leave it as a mega surface

Not quite accurate to what VX Ace is doing, but I think that's mostly because of kerning differences.

…ent outlines

Outlines should 1) Not change the position of the text and 2) Be visible even if the text is cut off from reaching the edge of the rect, without leaving the rect itself.
We're currently not drawing full text for the outlines like RGSS does, so we don't perfectly succeed at (2), but if we ever start doing that then the logic is already there.

Text transparency with outlines present still doesn't match Enterbrain's implementation, but I gave up on trying to figure that out.

…too-large dimensions.

I also fixed a small bug in how the wave position was calculated.

I ALSO fixed src_rects in general for waves. (How was that not noticed before now?)

Ruby is not guaranteed to delete bitmaps after any windows, sprites, etc that they are attached to. In the event that the attached object is not deleted before the next call to Graphics.update, this will most likely result in a segfault, as isDisposed() is not guaranteed to return true for a deleted bitmap.

Bitmap::invalid was added in an attempt to guard against this for sprites, but since the bitmap in question is deleted it's not guaranteed that the pointer actually points to null, which made the fix unreliable.

…lear

I'm implementing this via "child" bitmaps, which determine which part of the parent will be visible, manually shrink it if necessary, and send back new values for zoom and offsets.

Window contents and Planes are currently fully functional. Window skins still aren't supported, because it seemed unlikely that would be needed.
Sprites support everything except patterns.

The old code only functioned perfectly on squares.