[FINAL?] MOAIFreeTypeFont: fixed clipped letters when using returned value of processOptimalSize

This fix eliminates the possibility of penX becoming negative and giving a too-large return value for `MOAITextRenderer:processOptimalSize()` after subtracting the horizontal bearing of the first character.  I'm not sure why this check is even in there in the first place, but I added it back in late August 2013.  Removing this check would do just the same thing as this commit where penX previously became negative.  As for the cases where penX previously became positive, I haven't done enough testing to see if any characters would clip by removing this first character check.  The only case I encountered was with the font Abduction.ttf and a string beginning with the letter 'p.'