Gen

Build is passing.
NOTE: had to change some tests (see test_persistent_vector_implementation.clj),
since Number class mixes types … or somehow integers leak into matrices.

Did some reorganization and cleanup.
You can see "different behavior" if you change the vector mappings in pv_reals.clj.

Currently this can implement everything. Turns out we do not need, for now, to generate
any macros. 

Let me know if you think we need a convenience fn/macro to calculate template 
substitution vectors from a map.