Integrated optparse for current commands.
Added documentation about max_subs.
Rename max_subs to max_submissions in functions.

Avoids confusion over global and local variable names.
Added command-line parsing for max_threshold and count_word_freqs

max_threshold: maximum relative frequency in the text a word can appear
to be considered in word counts. prevents word spamming

count_word_freqs: only gather which words occur, but not counts vs.
count the number of times each word occurs
Clean up comments.
Added word count period option

period to count words over: day/week/month/year/all
Command-line parsing rework per suggestions.
Fix usage statement in command-line parser.
Rework command-line parsing

Use dictionary-like objects for options and arguments.
Check for correct # of args.
Changed raise Exception to parser.error
Renamed command-line param short forms, moved cl parse to main.
Merge pull request #16 from rhiever/command-line

Command line