Fix "audio LFO clicking" bug

[evangipson]

This happens with LFO on low attack notes. I think upping the attack might fix the issue after some googling: https://www.reddit.com/r/edmproduction/comments/1f0cya/how_can_you_avoid_that_click_when_using_side_chain/

[evangipson]

This is definitely due to LFO. I've tried to start combating the problem by adding a lowpass filter @ 2000Hz as well as playing less "echoey" arpeggios and chords: https://github.com/evangipson/midio/commit/6b75700ca272129a08476d160e89e8e5b572cd45

[evangipson]

This is definitely gone due to a few things:

• I've increased attack overall.
  • https://github.com/evangipson/midio/commit/6b75700ca272129a08476d160e89e8e5b572cd45
  • https://github.com/evangipson/midio/commit/51278e5f7bc1180edc7b3c64f23231abc2d2e706
• I've made the notes less "wall of sound"y by limiting how many notes midio will play per minute.
  • https://github.com/evangipson/midio/commit/8e035854e59a3bab927304e90e3f4b83363c150a
  • https://github.com/evangipson/midio/commit/c89befe5809503d7bdc7349197ba157fbf877301
  • https://github.com/evangipson/midio/commit/3af8addf99b8f464c23b47ddd20203bc6a72bfca

Inconsequentially, I've taken away the "LFO Probability" slider, and made the LFO "turn on" and be probable when you have both LFO Rate and LFO Depth higher than 0.