Freezes up

[joevenzon]

* if vdrift can't find it's data folder it should perhaps pop up a helpful dialogue instead of "freezing up" (this is pretty much a cross-platform issue)

This is totally my fault. The main.cpp code is horribly cluttered and hacked and needs to be refactored. I generally took the approach when originally writing everything that if an error is detected, the game should just keep chugging along anyway in the hope that maybe things will be okay.

Adding code to explain it can't find the data folder and quitting sounds like a good idea, though.