Specify include path as environment variable?

[Urs Liska]

Hi devs,

do I read the docs right in that additional include paths *have* to be
specified on the command line, with one or multiple --include options?

Has noone asked until now for being able to have LilyPond look for an
environment variable to add include paths?
I think many users will have their default toolboxes they use in all
projects, and it would make life somewhat easier (even if editors may
offer tools to create the command line automatically).

Any opinions?

Urs