Cleaned up some more things in FontTextureProcessor

XAdvance was incorrectly enlargened with line spacing (change didn't make any sense, value of XAdvance is not used anywhere)
Cropping rectangle width and height set to Subrect width and height, as XOffset and YOffset are essentially subrect X and Y

In GlyphCropper:
```C#
				glyph.Subrect.Y++;
				glyph.Subrect.Height--;

				glyph.YOffset++;
[...]
				glyph.Subrect.X++;
				glyph.Subrect.Width--;

				glyph.XOffset++;
```