about halfway though adding desktop notifications for period changes

Conflicts:
	script.js
Update README.md

Delete obsolete TODO list
re-added option for enableDayView (fixes schedule being broken)
Add long contributing guide (replicated from wiki)
[test] finished desktop notifications feature
 - desktop notifications
  - must be enabled in options
  - sends notification when period change is detected
NOTE: currently only runs on schedule update, so by default won't run while page is in the background

Conflicts:
	script.js
fixed desktop notifications
(was previously checking day change instead of period change)
various fixes for desktop notifications
 - removed notifications for passing periods
 - added notifications for period start (was previously only end)
 - added safety checks for browsers that don't support notifications api
 - removed debug code
added option to auto-close desktop notifications; fixed notifications
 - added option to automatically close desktop notifications after a given amount of time (0 to disable auto-close)
 - fixed notifications not displaying
bumped version number (V1.2.06); fixed derpy cherry-picking
Merge branch 'gh-pages' of https://github.com/HarkerDev/bellschedule into gh-pages
improved ap notification
 - renamed "ap" to more general "news"
 - added CSS for news messages