Adding multi-thread network downlaod for precache resource check on URL ...

[guruqu]

Server start takes too long because of single thread Url resource update check.
Made modification to use thread-pool and workers for concurrent Url checking.
Also output some status during the check so that user won't think their server hanged.

[guruqu]

I didn't do anything other than making the "header fetch -> hash check" process parallel, it speed up the starting process overall.
With regard to the some player making client ignore the "Resource Update/Hash Mismatch", I guess it's fine if that player/client don't want an "awsome updated experience".

[Dockter]

I have dealt with this issue for a long time.

I'll pull the PR down and test, if its golden I'll merge it.