Update main.py to current syntax

Change set_dims to dims = .  Remove prettyprint, for now initialize QCML
as debug to get numbered source output.

main.py still crashes on the Transpose tokens; see separate change to
qc_parser.py for attempted fix.
Updated README.md for new syntax

set_dims to dims =.  No prettyprint.  Changed one ref to
codegen("cvxopt") to codegen("python"), but wasn't sure what to do in
doc section describing different codegens (left HTML comment)
Merge pull request #18 from chinasaur/tidy/1

Tidy/1. echu: apparently "closing" != merging.