Add optional name to adlins data

For showing in legend
Show names of instruments in UI

Get an instrument name from the ADL instrument,
and show it in the legend.
Use 256-color escape commands to set colors

This avoids bright text looking bold but makes it impossible
to run in terminals with less than 256 colors.
Make time-synchronization work

Like in the Munt mt32 emulator, when the clock time goes out of sync
too much with the time computed by the sample rate and the number
of samples sent, resynchronize.
adldata.cc: Add name for 'nosound'

Make sure nosound is easy to recognize in the legend.
Change MaxWidth to 120
ui.cc: Color instrument name by type in legend

No sound -> dark
(pseudo-)four-operator -> bright cyan
Update README.md
Document AUDIO_SDL in Makefile
Update some messages...