make it possible to get information from the fonts within a font cache

Ignore-this: 9a7c61ff4e5a9e29760d1817507e2e0a

darcs-hash:20140916182904-fae1a-79343d6c832a2d7a68c7b613923ff29df1664a78
add a first simple set of module tests that check many of the faulty input possible and also a first check for the output, reached linecoverage 62%, goal: 100%

Ignore-this: 17a847002c8bfd198e3243acded39ceb

darcs-hash:20140916183053-fae1a-e72868255c7f1d3e6f018bfa7b7dc89353f857d3