Move constants to top of class for clarity
Change indent method to use non-destructive method
Rewrite if to be more Ruby-like
Move string generation logic directly into to_s
Move calendar date generator out of body method and simplify title method
Experimenting with formatting classes
Move formatting out to PlainFormatter class
move more stuff into PlainFormatter
Move PlainDate dependency out of Calendar and into PlainFormatter
Move PlainFormatter into separate file
Add color formatter
Change Color type classes to inherit from Plain type classes