Add more commands and configuration.

The effects of the plugin can now be activated and deactivated.
Improve documentation content and formatting.
Add line breaks to license file.
Update readme, improve formatting.
Fix formatting a line of doc missed in 7cd8314ab.
Fixes an issue introduced in bbead6b5f.

There was an issue where NumbersOnOff was not always working. I think
this fixes that problem.
Add a little clarification to documentation.
Merge pull request #26 from benspaulding/master

Add enable/disable commands, add documentation.