Minor five-fret engine tweaks

[raphaelgoulart]

• ALLOW_DESC_GHOSTS
  • Already implemented, just made into a toggle.
• ALLOW_GHOST_IF_NO_NOTES
  • If the next note is outside of the timing window, do not check for ghost inputs;
  • For some reason, in some rare scenarios it seems to allow ghosting when it shouldn't;
  • Increasing the ALLOW_GHOST_IF_NO_NOTES_THRESHOLD variable might alleviate that;
  • However if set too large, it might nullify the effect of the toggle.
• EASY_TAP_RECOVERY
  • If tapping to recover combo during tap note section, skip to first valid note within the timing window. This will make it easier to recover;
  • Only applies if combo is 0, and all following notes are tap notes, so it won't negatively impact FC runs.