Creating argparse subparsers for each engine.
Adding single-character abbreviations to flags.
Eliminating get_opts function, which has been replaced with argument parser from argparse in lib/get_opts.py.
Removing get_opts import from tests.py.
Replacing 'username' and 'hostname' with 'user' and 'host' to be concise and consistent.
Merge pull request #99 from bendmorris/opt_parsing

Fixing option parsing, and removing deprecated get_opts function