* Documentation/user/basic-notation.itely (Tuplets): add note

* Documentation/user/basic-notation.itely (Tuplets): add note
about nested tuplets. Remove BUG.

* input/regression/tuplet-nest.ly: update: remove manual hack.

* lily/tuplet-bracket.cc (print): use robust_scm2drul
(print): manually call print() for subtuplets.
(calc_position_and_height): add subtuplets to the
support. Vertically shift outer tuplet

* ly/engraver-init.ly (RemoveEmptyRhythmicStaffContext): set
remove-first for Lyrics, ChordNames and FiguredBass

* scm/define-grob-properties.scm (all-internal-grob-properties):
use ly:grob-array? iso. grob-list?
(all-internal-grob-properties): add tuplets grob-array.

* lily/tuplet-bracket.cc (add_tuplet_bracket):
new function