Ember.merge -> import merge
[BUGFIX beta] The `each` helper checks that the metamorph tags have the same parent.

In some cases, the browser may add or fix tags, which change the
parentage of metamorph tags (This problem happens frequently when the
developer does not include the TBODY tag inside a table for example).
This change prevents the framework to update or clean the underlying DOM
elements.

This helps to detect the issue described in #4273.

Adds `Ember.runInDebug` to call a function in debug mode only
[BUGFIX beta] Remove unreachable return in link-to.
Merge pull request #4502 from skurfuerst/patch-1

[BUGFIX] Fix Ember.Comparable and Copyable
Merge pull request #4404 from Cyril-sf/each_helper_check_metamorph

[BUGFIX beta] The `each` helper checks that the metamorph tags have the same parent.
[BUGFIX] Fix missing ES6 import for Ember.DebugAdapter.
Merge pull request #4506 from trek/es6-ember-merge

Ember.merge -> import merge
Merge pull request #4505 from rjackson/fix-extension-support-for-ember-data

[BUGFIX] Fix missing ES6 import/export for Ember.DebugAdapter.
Ensure that Ember.DataAdapter exists after Ember is loaded.

This fixes the underlying issue that #4505 was attempting to resolve
(but failed). #4505 ensured that the globals were setup properly upon
creation of an Ember.Application, but it unfortunately doesn't fix
Ember Data's initial boot.

After this PR the globals are all exported as part of the Ember boot
process (instead of during application creation time).
Merge pull request #4507 from rjackson/ensure-extension-support-is-available-after-boot

Ensure that Ember.DataAdapter exists after Ember is loaded.
Remove references to `window`.

These references are already setup properly using `this` which will work
even in non-browser environments or when we do not want to be working in
globals mode (for example when supplying `Ember.lookup` or
`Ember.exports` as mentioned in https://github.com/emberjs/ember.js/commit/305202f).
Generate independent module files.

This allows us to generate custom builds with specific modules embedded
without requiring the full package.

Specifically, this will allow us to generate an
`ember-template-compiler.js` without duplicating all of the details that
exist in `ember-metal/core`.
Merge pull request #4510 from rjackson/generate-independent-module-output

Generate independent module files.
Merge pull request #4509 from rjackson/remove-references-to-window

Remove references to `window`.
Ensure that ember package is in prod builds.

Fixes issue with Ember Data when using ember.prod.js.
Merge pull request #4511 from rjackson/ensure-ember-package-is-in-prod-builds

Ensure that ember package is in prod builds.
Merge pull request #4498 from rjackson/remove-unreachable-return-in-link-to

[BUGFIX beta] Remove unreachable return in link-to.
Fix String.prototype.camelize.
Merge pull request #4513 from rjackson/fix-camelize

Fix String.prototype.camelize.
Require ember-testing if present.

This ensures that the globals are setup properly if `ember-testing` is
present in the build.