Reimplemented font selection. Now use the new options rmfont, sffont and ttfont. Support of Linux Libertine (rmdefault), Source Code Pro (sfdefault) and Roboto. Added option sfmath. Sans serif math now in Soure Sans Pro and Iwona (greek letters) font. Options rmdefault, ttdefault, lato, beramono, sourcesanspro and other font related options removed.