Removed item update invocation when transitioning the odid live sim from pre-start to start

Removed the item update on first access of the resource content binary. This
 really isn't necessary and could confuse the DMC initiating the playback.

The live sim's pre-start state now can represent the initial conditions of
 the simulated time range - just with a non-moving live point. To support this,
 values being passed as parameters to the ODIDLiveSimulator constructor and
 start_live() are now properties - so they can be set prior to start_live().

Changed the ODIDMediaEngine res creation logic to not differentiate between
 pre-start and start. Also moved more of the live sim parameter initialization
 to find_live_sim_or_create(). And disabled the sim_started() logic so it
 no longer touches the item file (to induce a CDS update).