* Documentation/user/instrument-notation.itely (String number

* Documentation/user/instrument-notation.itely (String number
indications): new node.

* input/regression/new-markup-syntax.ly (texidoc): add circle.

* lily/new-fingering-engraver.cc (add_string): new function.
(acknowledge_grob): accept string-number-event as well.

* scm/define-markup-commands.scm (circle): new markup command.

* scm/output-lib.scm (print-circled-text-callback): new function.

* lily/GNUmakefile: move ifeq after include stepmake.make.