added support to strip out cygdrive and msys paths on windows. not sure how consistent

added support to strip out cygdrive and msys paths on windows.  not sure how consistent
the rest of the codebase is about using filename object where it should or could.  will
have to patch through making one-off code start using it.  parser bits got a simple new
set of functions for testing just alphabetical characters.  probably a lot of places
using their own code for this, if we didn't have that characterized before (just had
alphanumeric and numeric tests, as well as identifier, which is for variables and not
regular words).