Files tech not keep order by levels

[blond]

Files must be sorted first by levels and then by tech.

See enb/enb-js#5 and enb/enb-stylus#52

Example

?.deps.js

exports.deps = [
    { block: 'block' }
];

In ?.files target will be files in the following order:

level-1/file.ext-1
level-2/file.ext-1
level-1/file.ext-2
level-2/file.ext-2

Expected order:

level-1/file.ext-1
level-1/file.ext-2
level-2/file.ext-1
level-2/file.ext-2

[blond]

This is due to peculiarities of FileList.getBySuffix() — enb/enb#232.