fix ScreenGameplaySyncMachine crash

was not setting steps to null, caused access violations
Merge pull request #255 from sigatrev/SyncMachine

fix ScreenGameplaySyncMachine crash
dear github: our travis build is broken in a pretty serious way (The command "sudo apt-get install libc6-dev" failed and exited with 100), and I know this isn't travis-support nor the right place for it but I thought I should let someone outside of IRC know the reason for it thanks