Provide man pages for all bl-* commands

[ghost]

Some PoC work has already been pushed to the manpages branch. I intend to subsequently re-write all help files into man pages, and at that occasion also bring them up to man page quality -- eg the explainations for the conky commands are impossible to understand without prior knowledge and/or much trial-and-error play.

Instead of writing man pages directly, I am using pandoc for converting simple markdown documents into man pages.