added replace_add_fgfg with which TR10_inv is fast and powerful
Renamed ``fg_sub`` ``fg_div``; improved documentation; added a test
code clean up, added documentation
added case 'sin(x) + cos(x) -> sqrt(2)*sin(x + pi/4)';
added `debug` in 'replace_add_fgfg'
modified sorting in replace_add_fgfg to get deterministic results
if the keys are sortable
added various replacement functions in simplify_utils.py; removed code
with separatevars, matchers_division, matchers_add, matchers_identity
and artifacts from __trigsimp, by default `factor` not used.
fixed a few tests
added option ``use_factor`` to ``trigsimp``; added ``sec,csc``
fixed test
fixed a bug occurring in Python2.5
eliminated use of `factor` in `trigsimp`
fixed bug in `__trigsimp`
using ``_expand_exp`` after rewriting more simplifications are possible
fixed bug in use of option to_tan
added documentation
correct 2 formulae in _match_div_rewrite