Fix ff_restartround resetting twice when called with 0 prematch time
 * Also makes 0 prematch the default when using ff_restartround without a parameter (ff_setprematch is better for cases where you just want to add prematch)
Merge pull request #76 from fortressforever/fixes/ff_restartround

Fix ff_restartround resetting twice when called with 0 prematch time