Added a lot of comments fixed DivMod optimization added architecture dependand optimization for Mod/DivMod
Added a lot of comments
fixed DivMod optimization
added architecture dependand optimization for Mod/DivMod

[r4066]

jonashaag/libfirm,jonashaag/libfirm,8l/libfirm,libfirm/libfirm,8l/libfirm,MatzeB/libfirm,libfirm/libfirm,davidgiven/libfirm,killbug2004/libfirm,libfirm/libfirm,8l/libfirm,killbug2004/libfirm,davidgiven/libfirm,MatzeB/libfirm,MatzeB/libfirm,MatzeB/libfirm,jonashaag/libfirm,jonashaag/libfirm,8l/libfirm,davidgiven/libfirm,killbug2004/libfirm,MatzeB/libfirm,killbug2004/libfirm,jonashaag/libfirm,8l/libfirm,libfirm/libfirm,killbug2004/libfirm,MatzeB/libfirm,8l/libfirm,MatzeB/libfirm,davidgiven/libfirm,8l/libfirm,davidgiven/libfirm,killbug2004/libfirm,libfirm/libfirm,killbug2004/libfirm,jonashaag/libfirm,davidgiven/libfirm,jonashaag/libfirm,davidgiven/libfirm