Add/Replace Grid rhythm with overlapping method

[ricardomatias]

• Create grids with different resolutions
• Think of all the grids stacked vertically
• An interval tree with overlapping events

Strategy

• Roll the dice, HIT or REST
• Roll the dice, which resolution
• Check if the interval is empty
  • Empty -> add the event and move the cursor to the end of this event's interval
  • Filled -> Move the cursor to the next empty cell which is free and insert the event