Merge branch 'release/graphical_tweaks'
WIP: Added wakelock...

Added a wakelock to keep the screen on when running on Android, plus more
tweaks of the cars' appearances than you can shake a stick at, but mostly
because the last update made them look like synchronized goldfish.
Moved status to top.
Changed track texture.
Changed graphics some more.

- added a start/finish line.
- cars look a bit more like cars.
New track - Magic Garden
WIP: Added event broker.

The event broker decouples event publishers from event subscribers. It is
intended for relative infrequent events, eg, winning a race, crashing out
of a race, etc, so that systems can modify their behaviour accordingly.