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.
[BUGFIX] Fix Ember.Comparable and Copyable

without this change, Ember.Comparable and Ember.Copyable are "undefined".
[BUGFIX] Fix missing ES6 import 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).
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`.
Ensure that ember package is in prod builds.

Fixes issue with Ember Data when using ember.prod.js.
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.
[DOC beta] Fix `method` tag for `makeViewHelper` doc
The API docs were incorrect (and private) for `helper` because
it was being overridden here.
Now both `helper` and `makeViewHelper` will appear correctly.
Do not override local scope with imported Ember.run in Ember.Test.
[BUGFIX beta] Fixes weird Ember.A behaviour when one non-array argument
is passed.

Fixes #3815