Simplify upgrades system

Note that I have removed the speed upgrade from the UpgradeType enum. In
my opinion, because the speed upgrade is non-droppable, it should not be
considered an UpgradeType. Perhaps speed upgrades could be directly
applied to the player from the future code that handles the upgrades
store.

Also, my code is formatted slightly differently from the rest of the
code base, which is written in a style more reminiscent of C++ than
Java. I can fix this if necessary.
Merge pull request #7 from guoguo12/master

Simplify upgrades system
Path addition

Making the addition of new paths easier to handle. You would have to
update a certain variable if you added new paths, no more!
Added surrounding kill area.

Enemies that go super our of bounds are killed. This allows us to make
paths where the enemies do a drive by :D
testing stuff

will fix pathnum later today
Minor fix.

Put pathNum back to what it should be.
Merge remote-tracking branch 'upstream/master'