Add %t/%m for timelimit/memlimit in strategy definitions

This allows a strategy to call provers with the default timelimit/memlimit parameter. Example: "c CVC4,1.5 %t %m"

Remove set_session_timelimit/memlimit from server_utils: put them in controller_itp so that they directly edit the configuration of the controller. Edit parser of strategies to allow %t and %m.