Cleaned up some more things in FontTextureProcessor

Line spacing was incorrectly added to XAdvance (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++;
```
Width of cropping rectangle is not used anywhere. Height of cropping rectangle is checked to see if its larger than the line spacing, but is never actually used.

In conclusion, this does not affect how the SpriteFont gets drawn on the screen.