allow resolved module IDs to be non-strings

Closes #655.

__esModule for AMD modules and CJS with cyclical dependencies

distinguish between default and namespace imports from external module

options.preferConst to use const instead of var when creating statements

deconflict ES bundle imports

allow options.external to be a function

preserve debugger statements

This is the same as how babel does it. See https://goo.gl/KTGKyH.

allow rewrites of variable declarator inits

Update collapseSourcemaps to use class syntax post-620

warn if default and named exports are used together in auto mode

Fix a bug with no-treeshake

create new scope for classes, with class expression ID (if any) as sole name

sanity check output of load hook

Switch from Babel to Bublé

Add option to disable treeshaking

Add an option to add noConflict method to umd global

Normalize relative external paths.

report files causing transform errors

Use rollup-plugin-node-resolve instead of rollup-plugin-npm

Don't throw on single-length sourcemap segment

Update dependencies.

Add root: true to eslint config.

I left all the major-revision changes out because I figured they may require more work.

This prevents eslint from taking user's eslint config files that are
higher in the directory str...

Add useStrict option to ALLOWED_KEYS.

Windows...

Expand deshadowed shorthand properties

Allow external files to be non-existent, relative files. Fixes #532.

Prune dead conditional expressions more carefully.

Handle erroneous nested member expressions

Fixes 2nd issue in #565

Fixes #534.