Editor and driver support for multispeed

[Chordian]

Support for 2x, 3x, 4x... how high should we go?

Driver with one call for general maintenance and subsequent calls for updating effects only.

The multiplier value could be shown in the bottom right info area below the tables.

[Chordian]

This is a task migrated from workstreams in Slack.

[Chordian]

I personally believe this task should have high priority, even more so than support for e.g. sub tunes. Multispeed tunes are often created for the competitions at CSDb.