Preface: Sorry for the meaningless title and this mega commit. I'm too tried to thinking of names. I changed lot's of things that tightly depend on each other, and I saw it simpler to not to break apart them.

I tried out kanshi the first time today and I experienced a few flaws and missing features. I try to provide fixups for them.

This pull request indents to...

• Make program more user-friendly;
• Fix some (minor) bugs and make internals more robust;
• Add two command-line switches to achieve “IPC”.

Fixes #10 (missing ones), #11, #60, maybe #43, and provides solution for #56.

What's New

# Start kanshi to respond to changes in the background.
$ kanshi &
# Profile switcher:
$ kanshi -1p laptop-lid-up && echo Success
$ kanshi -1p laptop-external || echo External display not connected