New features in 1.5

* Simple tablature

* Many speedups, many slowdowns.

* More extensibility

* Figured bass support

* Improved beam formatting.

* Improved grace notes.

* Improved accidental handling and formatting

* Better spacing. Includes subtle details like optical stem spacing.

* More ancient notation support: mensural ligatures, porrectuses, more
shapes.

* Bracket piano pedals.

* Some entry optimizations.

* Font completely revised and improved.