Allow importing directories with index.ts files as relative external modules.

[coreh]

Hi there,

├ foo/
│  └ index.ts
└ bar/
   └ index.ts

Assume you have the project structure above, and that you'd like to require the file foo/index.ts, from file bar/index.ts.

With the current version of TypeScript you must use the

import foo = require('../foo/index')

CommonJS-based environments like node and browserify allow you to omit the index part, and use just require('../foo'). I think it would make sense for the typescript compiler to also allow that. (Considering it does look for index.ts in global external modules)

Thanks

[RyanCavanaugh]

We should discuss this as part of #247