[FEATURE] All pass EQ mode that changes phase.

**Is your feature request related to a problem? Please describe.**
If you have used REAPER's ReaEQ then you might have tried all pass mode. It changes phase at frequencies you as a user decide.

**Describe the solution you'd like**
I would love having this in this tool that I already use quite a lot.

**Additional context**
Thank you for this tool!