Update README to reflect recent changes
fixed ap-week schedules
 - changed schedules for 5/5, 5/6, 5/12, 5/13 (Mondays and Tuesdays of AP weeks) to 1a and 2b respectively (Extra Help instead of School/Class Meeting)
 - removed old changelog (should be kept in GitHub releases instead)
[broken] work on fixing date-navigation in day view
currently, url does not correspond to day shown in day view
Merge branch 'dev' of https://github.com/HarkerDev/bellschedule into dev
Update README.md

Delete obsolete TODO list
about halfway though adding desktop notifications for period changes
fixed May special schedules
 - Thu 5/29: Alternate with Extra Help instead of P8 (previously just a regular alternate) (41 -> 41a)
Merge branch 'dev' of https://github.com/HarkerDev/bellschedule into dev
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