Add WP Core Load graphic by Rarst.
Add plugins lecture.
Update filter resources.
Added week 4 readings.
Add enqueues APIs.
Add example plugin for enqueueing scripts.
More examples of problems when scripts aren't enqueued.
Add sample options page image.
Add options page API information.
Add sample options page to pinterest pugin.
Add pimpletrest settings image.
Finish basic APIs lecture.
Add AddThis image.
Add Homework 2.
Update Homework 2 dates.
Fixed some errors.
Add template hierarchy image.
Add introduction to themes lecture.
Add initial child theme and theme function lecture information.