slightly better error reporting
fixed bug in `Data.Spine.Parser.gap`
roughed out Distfixes
fixed bugs in associative binary infix and closed distfixes:
    reversal of priority fixed (mainly by reversing what I was doing)
    empty nodes excised
added and smoke tested half-open distfixes and non-associative infixes
documentation
fixed bug in distfix rewriting
added Functor for (quasi)spine; finally renamed QuasiSpine -> Quasispine
documentation
cleaned up some leaky type synonyms
built a prototype Environment module, but I can't figure out how to run the monad
rough drafted a working EnvironmentT after having added the restriction that the inner monad m must be an instance of Data.Ref.C
documentation
apparently, I added a Gensym module...
attempted generalization of Gensym
functions to convert to an immutable env
rewrote parser, untested
parser enchancements, documentation, bugfixes; SExpr type; fixed Hierarchy Quasispine instance