Changes:
- Usage determination transferred back to argparse (it wraps).
- Added complete description of lemonbar script to wm-widgets.rst.
- --interval and --height got their arguments clarified by metavar: it was not
clear what units they use.
- --bar-command got its metavar because it is better then default BAR_COMMAND.
- --bar-command short variant is now -C.
Most of the files are empty and need to be copied or rewritten from the
old docs. Font patching docs have been removed entirely and will be
moved to the powerline-fontpatcher repo.
Ref #769