GRAPHICS: Allow to query the bounding box of chars/strings drawn with Font API.
GRAPHICS: Allow negative xOffset in TTF.

This should improve the visual looks of many fonts. However, it might result
in the first line of the glyph to be drawn left of the position specified in
drawChar.
Merge pull request #500 from lordhoto/ttf-improvements

Improve TTF Rendering (includes Font API changes).