expanded complement_map to include degenerate bases

used [this
page](http://arep.med.harvard.edu/labgc/adnan/projects/Utilities/revcomp.html)
as a source for the maps, will use a different source for the tests.
added tests of the degen complementing

pulled test data from [this
page](http://droog.gs.washington.edu/parc/images/iupac.html) which is different
then where the mapping in the library code came from (see previous commit).