Separated the code that renders comments as text in debug mode into its own branch.
Added missing return type to SpanStyles.primaryColor getter.
Added getter for current primary alpha to SpanStyles.
Changed Drawing to an accumulator of DrawingStyles.

This fixes the following:
- Declaring \pbo before \p1 used to have no effect, but now it does.
- Multiple DrawingInstructions parts used to cause an error instead of being treated as separate drawings.