Prevent accidentals and articulations from moving over leftmost NonMusicalPaperColumns.

Prevent accidentals and articulations from moving over leftmost NonMusicalPaperColumns.

Inversely, allows accidentals to tuck over change clefs and prevents ledger lines
from overlapping barlines in cramped situations.

This is done by allowing the pure-from-neighbor-interface to add
extra-spacing-height to certain non-musical grobs and removing the
blanked skyline-padding applied to NonMusicalPaperColumns.