Ability to read bemObjects by levels, not randomly.

[Yeti-or]

Currently bemObjects are pushed from different levels.
what about adding some API like this:

walk.sorted([
    'libs/bem-core/common.blocks',
    'libs/bem-core/desktop.blocks',
    'common.blocks',
    'desktop.blocks'
], config)
    .pipe(stringify())
    .pipe(process.stdout);

so walk will flush objects randomly from levels,
walk.sorted will flush it grouping by levels, in order of levels in array.
@blond what do u think?

[blond]

I agree that such a possibility must be in the API, but I don't like walk.sorted method.

Also I do not want to bem-walk has a complex API. What can we do in my opinion:

1. Sort by default (if this does not slow down the scan)

   The order will be taken into account:

   walk(['common.blocks', 'desktop.blocks'])
       .pipe(stringify())
       .pipe(process.stdout);

   The order will not be taken into account:

   walk('*.blocks', config)
       .pipe(stringify())
       .pipe(process.stdout);

2. Add option the levelOrder option

   The order will not be taken into account:

   walk(['common.blocks', 'desktop.blocks'])
       .pipe(stringify())
       .pipe(process.stdout);

   The order will be taken into account:

   walk(['common.blocks', 'desktop.blocks'], { levelOrder: true })
       .pipe(stringify())
       .pipe(process.stdout);

   The order will be taken into account:

   walk('*.blocks', config, { levelOrder: ['common.blocks', 'desktop.blocks'] })
       .pipe(stringify())
       .pipe(process.stdout);

3. Add option the levelOrder option with true value by default

   The order will be taken into account:

   walk(['common.blocks', 'desktop.blocks'])
       .pipe(stringify())
       .pipe(process.stdout);

   The order will not be taken into account:

   walk('*.blocks', config)
       .pipe(stringify())
       .pipe(process.stdout);

@Yeti-or, what do you think about this API? May be you have other ideas?

[blond]

In terms implementation it's like #20.

[blond]

The #16 issue have bean closed, so we can add ordered option.

walk(['common.blocks', 'desktop.blocks'], { ordered: true })
    .pipe(stringify())
    .pipe(process.stdout);