Add help text
Add media upload to help text
Refactor media widget
Add help text to tests
Fix multiple choice items and associated tests
Consolidate if statements
Merge branch 'master' into help-text
Merge branch 'master' into help-text
Use base path instead of data
Merge branch 'master' into help-text
Add help text feature flag
Merge branch 'master' into help-text

Conflicts:
	src/parser.js
Require core before itemset
Add support for mug interaction with data tree writer
Allow mug to interact with control tree writer
Clean up label writing
Writer: moving code around

Move createOpenControlTag out of createControlBlock
Move mug-specific writer options into mug options
Refactor writer so Repeat is no longer special
Refactor writer so ReadOnly is no longer special