Support globs as levels

[qfox]

I think we should support globs.

bemSrc('*.blocks', ...)

Also we can use globs as bemdecl (?) or techs options:

bemSrc('*.blocks/button/**', ...)

cc @blond Can you please describe this proposal more widely since you are the author?

[blond]

Also we can use globs as bemdecl (?) or techs options:

I meant that we can use something like:

bemSrc('*.blocks/button/**/*.css')

[qfox]

I guess you need to write specification for these wildcards first.