Fixed issue with xargs 'env' too large

Cygwin inherits Window's enviroment settings.  This also means Cygwin
is limited by those settings (ARG_MAX is very small compared to Linux).

In order to fix this, each operation exports the required functions
before starting the script.  In addition each operation cleans up prior
functions that may have been exported (by unsetting them) from previous
operations.
Update to Version 0.18.2_cygwin