Added some other useful functions.
Merge branch 'multi_shell' of https://github.com/cwaldbieser/grouper_shell_wrappers into multi_shell
Jython shell front-end can take a script to execute as a command line argument.

Extra args are passed to the script.
Removed all the initEnv stuff; added option to extend the classpath.

The initEnv code was confusing-- I believe it is so you can source gsh.sh to
get a proper environment.  If so, you can still do that.  It doesn't make
sense for the script engine wrappers.

The -c option now lets you extend the CLASSPATH without modifying your local
environment.
TYPO: That option should be `-c`.
TYPO: It *really* should be `-c`!
Don't fail if readline support is broken.