the beginning of a gsexec environment - better gsexec, and a test harness!

README.md is out-of-date.

Makefile:
- tweaked tests
- added test ./bin/gsexec t/Test.t
- commented out RESOURCE stuff

new ProcSet/Test:
- a postscript test harness, with POD!

new ProcSet/gsexec_init:
- contains necessary initialization for a gsexec environment, and is loaded automatically by gsexec

renamed gsexec.c -> src/gsexec.c:
- don't use getenv("HOME") -- use getenv("GSEXEC_LIB") instead which takes a comma-delimited list of directories
- include -I$(PREFIX)/gsexec/resource
- give a gs prompt if no args instead of help
- help is called with -H as the only arg
- gs option -P is no longer hardcoded in
- change order of options put in v
- the "about to run" message is not displayed unless -V
- "about to run" changed to "command", and prints to stderr
- commented out RESOURCE stuff
- load ProcSet /gsexec_init instead of -c shebang magic

new t/Test.t:
- test file for ProcSet/Test

t/fizz.psx:
- added -V flag
- added checks on ARGUMENTS content