Implement left-side overhang compensation for the first character of a string in SpriteFont.Measure and DrawInto.
Add an interactive test case for issue #1355.
Fix DrawInto not properly handling left side overhang of characters.
Fix SpriteFont.Measure not completely compensating for negative left side overhang of characters.
Merge pull request #1606 from kevingadd/spritefont_left_overhang

Implement left-side overhang compensation for SpriteFont (#1355)