paid a lot of tech debt in memory management, cleaning up memory leaks and bad frees and stuff

Also created _t_morph which we were doing manually in _r_reduce.
added some comments in semtrex header
fixed invalid memory read problem in semtrex
fixed memory leak in _t_remove
added explict way to add zero sized tree nodes: _t_newr
improved semtrex FSA dump and symbol_name dump for error cases
renamed _t_remove and _t_detach
fixed some bugs in paths and labels
cleanup
first pass on serialization of receptors in place