Add library font preference.

* Add font selector to the preferences.
* Move row height preference from Interface to Library.
* Add controls for changing the font size:
  - [Library],font_size_increment
  - [Library],font_size_decrement
  - [Library],font_size_knob

If the row height is smaller than the font-size the larger of the two is
used.
LateNight: remove font tweaks

Conflicts:
	res/skins/LateNight/style.qss
Support loading fonts from res/fonts.
Package fonts in res/fonts.
Add OpenSans to res/fonts.
Switch Deere to Open Sans.

Reduced all point sizes by 1. Not sure why but Open Sans renders a tiny
bit larger?
Review notes.
Merge pull request #422 from rryan/font

Add library font preference.