Stared chords (e.g. [F*]) are often used when there are two ways of
playing the same chord in the same song. The starred variant is the one
that is different from the "main" variant. This commit marks the starred
chords as important, using \gtab* instead of \gtab.
Notes:
- Debout_Sur_Le_Zinc/La_declaration.sg: the non-stared B7 is marked as
important as well, since it does not follow the standard (barre)
variant.
- Jimi_Hendrix/The_wind_cries_Mary.sg: all the chords are marked as
important, since they are all non-standard.
- Oldelaf_et_Monsieur_D/J_veux_etre_muscle.sg: starred chords were
used for the chorus and non-starred for the verses; it is now the
other way since it is the chorus that use the standard chords and
verses that use alternative chords.