Fixed a typo: mConcurrectConnections -> mConcurrentConnections

That's what you get for only copy&pasting variable names.
Rewrite of AIPerService::add_queued_to

This should fix any 'stalls' with zero added requests for mesh.
Fix global connection threshold not to count non-approved queued request as being in the pipeline.

This make more sense when comparing the threshold against 2 times the
maximum allowed total connections.

As a result, textures won't stall when there are around 128 mesh
requests queued.
Temporary hack to easy the mesh connect timeout problem.