Add lvar aware postcondition emit for while

@dkubb Pls no fsck. Still unsure, refactored this a zillion of times.
Probably gonna write a state machine that I can run next to the AST
walkter.
Merge branch 'master' into lvar-aware-postconditions
Correctly reproduce local variable assignments with preconditions
Add class descriptions
Remove unnneded lvar assignment
Fix YARD docs
Add missing YARD tags
Simplify diff generation
Adjust flay score