added multitrack domain to main
added multitrack domain to main


BerkeleyAutomation/rlpy,rlpy/rlpy,silgon/rlpy,BerkeleyAutomation/rlpy,MDPvis/rlpy,rlpy/rlpy,silgon/rlpy,silgon/rlpy,rlpy/rlpy,BerkeleyAutomation/rlpy,imanolarrieta/RL,imanolarrieta/RL,MDPvis/rlpy,MDPvis/rlpy,imanolarrieta/RL