Pulled a few more substitutions out of nlp query, before I get into the
block-based substitutions
Moved most pre processing substitutions out to a pre processing substitutor
Made it possible to defined multiple substitution blocks
Made nsub!#changed_in include the line number as well as the class
Added some extra test cases to check the last few pre processing
substitutions
Added back in a substitution for every n days/weeks/months

Only works for days right now - construct interpreter needs fixing for
that I think