Prevent duplicate invocations or race dontision in SP.CompleteMovement()

This can happen under poor network conditions if a viewer repeats the message send
If this happens, physics actors can get orphaned, which unecessarily raises physics frame times
Actually put IsChildAgent = true inside the lock, otherwise there is still a small window for race conditions on duplicate CompleteMovement calls
Stop exceptions being generated on agent connection if a telehub object has been deleted or has no spawn points.
Add "generate map" console command to allow manual regeneration and storage of maptiles

Primarily for test purposes though could be useful if one prefers to manually update the map tile
Properly dispose of drawing objects to reduce/stop memory leakage on generating map tiles with the MapImageModule and TexturedMapTileRenderer (the current defaults)
Merge branch '0.7.6-extended' into 0.7.6-post-fixes
Skip IClientAPIs that don't implement IStatsCollector (such as NPCAvatar) from the "show queues" console report to stop screwing up formatting.

"show pquques" already did this
minor: correct the usage statement on the "show image queues" console command - should not have been "image queues show"
minor: remove long unused state queue from "show queues" console reports