Allow multiple wobs to be run together

[StephenCoady]

If it was possible to have multiple wob bars and have each one appear differently this application would be a lot more useful.

The use case I am thinking of is when you change brightness it is a sun icon with the overlay and similarly, when you change the volume it is a speaker icon.

I know this probably ties into #7 but it is slightly different.

Happy to work on this myself if someone had any ideas about how it could be done.

[francma]

You can run multiple wob instances with different colors or set color at runtime by sending 20 #color1 #color2 #color3 to STDIN instead of just 20.

I'm not planning on adding text or icons.