Clear IsBusy a bit earlier in the load process.

Perks and Shouts don't affect appearance, so the character is "ready" before they're applied.
Clear local PlayTime float when actor is deleted.

This makes sure that they'll reclaim their weapons and armor when they're loaded again on the same save.
Mark character as non-busy even earlier.
Alcoves now check for stuck validation and time out after 2 minutes.

For now the timeout just notifies the player of the problem and tells them to go to MCM. Perhaps they should auto-reset, but on slow systems with a full Shrine that might cause characters to be removed while still loading. Closes #72, though: it should now be nearly impossible to get the Shrine stuck in an invalid state unless script latency is intolerably high.