Feature: Make default synth used for MIDI File Playback User Selectable

[ZincT]

Currently when you drag and drop a MIDI file onto CbB with no project opened it will automatically open a new project with an instance of TTS-1 and all of the MIDI track outputs set to TTS-1.

This is really useful and I wouldn't want to change this behaviour except to have an option for the user to choose whichever instrument VSTi/DXi should be used by CbB for MIDI file playback. The default should continue to be TTS-1 but, for example, I would like CbB to use the Roland Sound Canvas VA VSTi.

I can imagine some kind of preferences option like the one I made up below. You would click on the Browse button to select a different default MIDI synth.