StdScheduler: Split into StdSchedulerWin32/StdSchedulerPoll/StdSchedulerMac
C4AbstractApp: ScheduleProcs timeout parameter defaults to 1000/36 instead of -1 so the timeout is not determined to be infinity down the road, leading to mac version not getting out of the poll call anymore
Merge branch 'master' into macscheduler
adjusted some particles (f.e. smoke slightly brighter, foundry more subtle)

see http://forum.openclonk.org/topic_show.pl?pid=25749#pid25749 for further information
Merge branch 'macscheduler'
add icon for maze
make the story of MineRescue more believable (so the "trapped" clonks can't climb, eh?)
Proofreading and adding missing (German) descriptions of scenarios
cmake: Only add StdSchedulerMac.mm when APPLE platform