A new usage layout

There are two goals to this patch:

    1. This is intended to introduce more consistency into the output,
    regardess of whether it is a missing opt/arg, or an error or a help
    requested usage message. *All* of those situations still result in
    a usage message that starts with "usage...", instead of leading
    with the different "[ blah blah ]\n\n".

    2. This patch also adds the comment/synopsis for the current
    command to the output when it is a help request. This also helps to
    differentiate between missing/help conditions. At the moment we
    don't accept a comment string for the top-level class - this should
    probably be added at some point.
Distribution version 0.1.1_1
Put the error message at the very end of the usage

When colour was used, having the red text appear mid-way through the
usage message was a bit jarring, and if colour wasn't used then the
error could get a bit lost. I feel now that the error at the bottom
draws my eyes better. Similar to the last "fatal: " message from tools
like git.
Get rid of the grey colours

Too confusing, just the yellow and the red are less complicated.
Cleanup the example/paint script
More usage yak-shaving

I'm starting to realize that colours at least should be configurable.
Merge branch 'feature/usage' into devel
Distribution version 0.1.1_2