Move initial positions leftward somewhat
Add enemy class
Rename Physical's collision method (bugfix)
Set enemy gravity to 0
Add an enemy to the levelroom
Add mouse display HUD thingy
Make horizontal and vertical lines look less bad
Add a box platform thing to the middle of the room
Rename DashPowerup's guy to player
Merge branch 'topic/ghi/35' into dev

"Fixes" Github issue #35

I'm an idiot - this wasn't an actual issue that needed development, but
I'm glad I worked on it because it helped