Merge pull request #44 from kryger/master

Another entry - thanks
Update README.md
Improved styling
Using jQuery for low-level DOM operations
Mousetrap for keyboard handling
Speed as a parameter to move, not set inside function
Local variable 'plane' -> 'feature' to avoid ambiguity
Zooming out if plane disappears from the SVG layer (lame workaround
for a bug...)
Misc cleanup
"What" uses the same font as the rest of the instructions
Returninig from zoom-out happens every other cycle, not immediately
in the next tick (to avoid jumping up and down)