…ate build instructions for Cygwin yet

… in building on Cygwin; temporarily disabling Win32 for now while we get Cygwin up and running

…convert the path to a Cygwin path

… sourced when needed in each build stage

…on appveyor:

- test_argparse
- test_ioctl
- test_os
- test_py_compile

…eption' even if the last command existed successfully

this should work around that...