(option_map::parse_options): Rewrite.  Do not modify the input
string, allow !foo as a shorthand for foo=0, and support K and
M suffixes for values.
* src/tgbatest/randtgba.cc (cons_emptiness_check): Simplify.
* wrap/python/spot.i: Process optionmap.hh.
* wrap/python/tests/optionmap.py: New file.
* wrap/python/tests/Makefile.am (TESTS): Add it.