Added XDG basedir config handling.
Added config file reading.
Read --directory setting from config file.
Add --no-backup option.

I only really added backup files to placate Kevin, and it was only a matter of
time before they became optional.  However, I've changed my opinion since
ca26bfd6 I'm setting backup to 'on' by default.
Support subcommand defaults in config file.
Make coloured output selectable in config file.
Support per directory config file.

This is really quite useful for lazy per-project task configuring. Thanks to
Nathan for the idea.
Read system level configs.

This shouldn't really be necessary, but if you're going to support the spec...
Merge pull request #5 from JNRowe/feat/config_support

Feat/config support