Merge pull request #224 from xycaleth/master

Fixed code to compile under clang on Mac (hopefully Linux too).
Fixed a bug in SP where moving along walls at certain angles allowed for players to accelerate beyond control. Thanks to @Agustinlv for this fix.
Fixed #223: Removed fx_flashRadius, in favour of an auto-sizing flash radius. Also
reverted 73e6c9177b, as it broke more than it fixed.