Cleanup annotation and font-size
The annotation-property was intended as a debug mechanism, and
has no control of positioning.
Its usefulness for the user is limited.
Thus it makes no sense to provide interfaces/properties to configure its printed output.
Currently RepeatTie and LaissezVibrerTie miss the annotation-property, though. Only Tie has a set font-size-property. Slur and Beam use a fallback in beam.cc and slur.cc. This leads to frequent programming errors if compiled with the check-internal-types option and inconsistent font-size. Furthermore custom-overrides for curve-stencils needs to always special-case Tie.
Thus give all of Beam, Tie, RepeatTie, LaissezVibrerTie, Slur and
PhrasingSlur the annotation-property in beam.cc, slur.cc, tie.cc and
semi-tie.cc. (Where missing.)
Make annotation an internal property.
Delete font-size for Tie from define-grobs.scm.
Delete font-interface from beam.cc
Use the same font-size-fallback in tie.cc as in slur.cc
Use the same font-size-value in beam.cc as for the other grobs.