* Documentation/user/changing-defaults.itely (Creating contexts):

* Documentation/user/changing-defaults.itely (Creating contexts):
new node.

* lily/grace-iterator.cc (process): descend to child for \grace.

* lily/timing-translator.cc (initialize): Timing_translator adds
Timing alias by itself.

* lily/context.cc (add_alias): new function.

* scm/lily.scm (tex-output-expression): new function, eval within
drawing API. Guards against eval vulnerabilities.