Fix number of lines in UI::PrintLn
Only show portamento warning if !=0

This avoids a flood of warnings when resetting controllers.
Revert 64c20ce (Start audio after first samples)

Solve this in audioout.cc, not in each executable.
Handle audio start/unpause automatically for SDL
WIP
Implement `all sounds off` (controller 120)
Warn when playing missing instrument

Mark instruments with peak amplitude <0.5 as having no sound.
Log a warning when one of these is played.
Show name as instrument bank as well as number

At startup show the name of the selected instrument bank as well.
Fix off-by-one error in MIDIsymbols