Re-factoring mood?

Moved a bunch of classes to their own individual files.  Nothing too exciting.

Debating what my next-step is:

1.) Go through each object type and make sure the various commands work (e.g. "click algebra-ln" when the "algebra-ln" button is not exposed).

2.) Finish the parser so that it can read from command.

3.) Build a GUI so that you can select various activities (this is probably a no-no, as it messes with the GUI state, and Sugar seems pretty finicky about certain things if they get set-up twice -- which screws up spawning other activities).   Also have considered implementing this functionality in the parser (e.g.  a command with the syntax "activity Calculate").  However, that has implications of its own, since actions are only called after some Gtk events are thrown around... which only happens after the Activity has been started.  You get the idea (chicken-egg).