Fix a bunch of problems with GOTV delays

[nickdnk]

So it turns out that the GOTV-related stuff I made in #821 caused some problems, as I had slightly misunderstood how the GOTV delay affected recording of demos. This PR fixes all that, and I've tested it a lot.

I've taken tv_delay parameters out of the sample config files and discouraged people from putting tv_ in their warmup/live, as changing the delay while changing game states messes with the demos. I took out tv_delaymapchange as well, as Get5 automatically makes this adjustment when a map ends. tv_-commands should be added to the server permanently (by some other config) or set in the match config cvar section, so they don't vary between stages.

Added a separate section on GOTV to the docs also.

This also fixes some race-condition related stuff in the Get5_OnDemoFinished event if quickly ending/starting matches, using DataPacks