Started logic redesign to use MVC [in progress]
Started rewriting Changes

Renamed to Commands to correspond to the design pattern used.
Block_insertion command
Remade the Block_rotation command
Clean up to make it possible to compile
Compilable state - now proceeding to write tests.
Added back all old working tests + Block_insertion
Rewritten tests to work with new commands.
Generalized Observer class.
Generalized observer Subjects class.