added even more abstract interface for execs to implement, turned out to be useful for the RockExplore lesson
added even more abstract interface for execs to implement, turned out to be useful for the RockExplore lesson


git-svn-id: c57083cae03de9a0803956a3abd65044d17a906b@884 3bbcab3b-a713-480a-a40a-1fdaa183d0c8

trey0/zmdp,trey0/zmdp,trey0/zmdp,trey0/zmdp,trey0/zmdp,abhishekcs/RLFD-Project,abhishekcs/RLFD-Project,abhishekcs/RLFD-Project,abhishekcs/RLFD-Project,abhishekcs/RLFD-Project