Unify prism script and CSS discovery routines
Add MIME type for UTI imports
Make analyser shut up about warnings in dependencies
Split up Prism scripts to reduce file size

Part of the implementation for #2
Make Prism theme configurable and fix script dep
Try to also include the “extras” variant
Refactor rendering logic into separate class
Formatting and removing dead code
Merge branch 'document-refactor'

Conflicts:
	MacDown/Code/Document/MPDocument.m