removeCombined and shared dependencies

[platinumazure]

I'm in a codebase where we have modules that are composed both of self-contained dependencies and shared helpers. We'd love to use removeCombined but unfortunately some files need to stick around for future module combinations.

Example directory structure:

+ helpers
| |
| -- someHelper
+ src
  |
  + module1
  | |
  | -- mainModuleFile1
  | -- selfContainedDependency1
  + module2
    |
    -- mainModuleFile2
    -- selfContainedDependency2

In this example, src/mainModuleFile1 and src/mainModuleFile2 are the modules that should be generated. Each one requires the "selfContainedDependency" file in its folder plus helpers/someHelper.

A few possible ways around this:

• Allow removeCombined to be a predicate function (returning true/false, where true implies file can be safely removed as if removeCombined=true had been set)
  • If r.js supported a predicate removeCombined function, we could remove only the "selfContainedDependency" files and leave the helpers/someHelper file.
• Add an option to avoid removing files that are outside of the directory the main module file is in (I'm not a fan of this due to coupling module names with filesystem which might not work for plugins)

I'm happy to work on a pull request if you are willing to accept either of the options above or have any other suggestions.