tabless version of amazing gracew
add samba em preludio and the set of its chord forms, not all of which
are supported yet.  F#7/+5.
add more tests for unparseable chords ?/+5 rather than ?/G#
Romanization of chord sheet, including command-line -r to enable.
Added chord summary (set of chords found, sorted).

However, we don't have an interface for when and where it should
be presented at the moment, so I'm just showing it in a trace!