Add \#160 conversion to FormulaParser.

This is a non-breaking space. I just convert it into a regular space.
Reorganizing for Multiple Choice questions.

Calculated questions aren't the only ones that needs to be parsed
apparently, we need to worry about multiple choice questions too.

Going to organize the blackboard parser package into subpackages based
on the question type.

Also added a QuestionTypes class for better handling of question type
comparisons.
CalculatedParser implemented.

Moved all Calculated question specific parsing out from BlackboardParser
and into CalculatedParser.

BlackboardParser now will check for question type and then call the
appropriate question specific parser to handle the rest of the parsing.

Multiple Choice questions next.