Specify new default values to be used by all subsequent calls to midi_* fns. Merges the specified values with any previous defaults, rather than replacing them

Introduced in v3.0

Example

# Example 1

midi_note_on :e1
use_midi_defaults channel: 3, port: "foo"
midi_note_on :e3
use_merged_midi_defaults channel: 1
midi_note_on :e2

# Sends MIDI :e1 note_on with default opts
 
# Sends MIDI :e3 note_on to channel 3 on port "foo"
 
# Sends MIDI :e2 note_on to channel 1 on port "foo".
# This is because the call to use_merged_midi_defaults overrode the
# channel but not the port which got merged in.