RemoveEmptyStaves and \with

[Neil Puttock]

Hi,

Context modifications inside an identifier are great, but in the case
of \RemoveEmptyStaves, there's a nasty surprise waiting for you: since
it's defined inside a layout block (as part of engraver-init.ly), it's
unusable within a music block.

\new Staff \with { \RemoveEmptyStaves } { c4 }

or

\new Staff \RemoveEmptyStaves { c4 } % even better, gets rid of nasty
\with block :)

-> error: unknown escaped string: `\RemoveEmptyStaves'

Why don't we move its definition to a separate file (e.g.,
`context-modifications-init.ly')?  I'm sure there are other mods which
could usefully be defined (e.g., \blankStaves for manuscript paper),
so a separate home for them makes sense.

Cheers,
Neil