Shelter rc4

a3:

* capture points no longer take sodding ages to de-cap (had to use another hacky method to get this working, thanks Valve)

* fixed an announcer line playing at the wrong time

* added spectator cams

* added a couple more signs

* a few other minor changes not worth mentioning

a2:

* added round timer

* capture points now unlock after 30 seconds (like in KOTH maps) (the control points still appear as unlocked on the HUD, not sure what to do about that atm but it's not a huge concern anyway)

* fixed rounds ending while one capture point is being contested

* fixed respawn times

* increased capture times from 20s to 25s

* fixed a couple of broken overlays