bug: keep repeating timers running after a throw, and gone after an unload

[lukepolo]

• SwiftlyS2 drops a repeating timer for good the first time its callback throws; TimerUtility.Repeat and the practice plugin's 1s and 0.1s loops now catch and log instead
• SwiftlyS2 also runs a repeating timer's first pass even if it was cancelled before that tick, so a killed timer now checks before it runs
• SwiftlyS2 only tears a plugin down once Unload returns, and a hot reload loads the new build either way; the match and practice plugins' unloads can no longer throw, and the match plugin clears its timers in a finally