Enhancement: Rewrite parsing and processing system

[cassava]

Right now the parsing and processing system using five primary functions:

• parse_argument_list()
• _process_group()
• _parse_group()
• _process_unit()
• _parse_unit()

It would be better if we could parse the entire thing once, turn it into some kind of object, and have another method read that object, and do the searches based on information from that object. That way, the code wouldn't be spread all over 5 functions, but clearly modularized into two separate functions.

[cassava]

On the other hand, why fix what ain't broke?