Be able to use rates "beyond 100"

**Is your feature request related to a problem? Please describe.**
Some users want even faster rates than what synthesizers produce

**Describe the solution you'd like**
- We could allow rates beyond 100
- or we could have a "boost" switch which makes "100" actually mean much faster than the current 100.

In some cases, the current maximum 100 is not actually the maximum that the synthesizer supports, so we could enlarge the range.
Additionally, sonic can be used on-the-fly when the module supports server-side audio, to boost rate.

Discussion would be needed to determine what's best