Makes it hard to test anything because `EditorBeatmap`'s `Update` method
updates whether a beatmap has timing or not (enabling the placement
controls).
Also adds a basic timing point to allow for better testing.
If we are going to continue to let the underlying clock process frames,
there needs to be a bit of lenience to allow the backwards seek on
resume (to play back over the freq ramp period).
The test is meant to be ensuring we don't skip the full offset amount,
so div10 seems pretty safe.