start splitting this up
switch from optparse to argparse
add debug logger, default position args
move arg parsing stuff into parse_args
add some tests for parse_args, argpase is weird
Set any global_args as defaults on parser

Even though parser has global_parser as
parent, it doesnt inherit it's values.
So after parsing the global_args from
global_parser, set all of the values
as defaults on the new parser.
make tests pass

add one for "comment" mode
no pygithub yet
handle commit comparisons with no patch

Aka, file renames or the like.
update readme