use spirit parser for reading annot file

use spirit parser for reading annot file
This basically duplicates tristans original annot parser using boost::spirit.
That was more complicated than I thought, and required implementing
a functor struct that stored data when the class was instantiated and then
performed some action with the operator() was called. Look at the comment
at sequence.cpp:push_back_annot for more descriptions of how that worked.

I improved the annotate_from_sequence unit test to not use hard coded values.

I have the start of a unit test fort the annot parsing code.
(currently it parses a string and then dumps out the result)

Though I did run the gui using this code and annotations did show up in roughly
the right places.