Remove stupid suggestion in TODO.

Removing items during willChange prevents run-time coalescing.
Add API docs for Ember.reduceComputed and Ember.arrayComputed
Ember.computed.sort compares proxy correctly.

When an item property changes the item is removed and re-added, thus resorted.
When being removed, it is necessary to binary search using the previous value,
as that is what's determined the ordering.  However, because we coalesce changes
(and thus move them to a subsequent run loop) items will have their *new*
values.  Because of this, `Ember.computed.sort` uses a proxy object in this
case.

This commit makes the proxy object correctly compare itself to the proxied
object as 0 (ie equal).

This addresses issue 1 in #3273 but does not fully address issue 2.
Merge pull request #3285 from hjdivad/fix-3273

Fix issue 1 in #3273.
Standard test handling of Ember.TEMPLATES teardown
Whitespace
IE <= 8 does not have indexOf or map on arrays. Fixes #3286
Removed incorrect note in docs - Fixes #3111
Merge pull request #3278 from bmac/document-reduce-computed

Add API docs for Ember.reduceComputed and Ember.arrayComputed
Merge pull request #3287 from lukemelia/index-of-ie-fix

IE <= 8 does not have indexOf or map on arrays. Fixes #3286
Optimization per @kselden - indicies is only ever a native array, so the ArrayPolyfills.indexOf is more efficient than the one from EnumerableUtils
Merge pull request #3288 from lukemelia/index-of-ie-fix-tweak

Optimization per @kselden
`Ember.computed.sort` fallback to guids.

It is now legal for a user's sorting to result in different items counted as
equal for purposes of sorting.  Obviously the relative order of items that are
sort-equal is not guaranteed.

The implementation simply uses guids as a deterministic tie-breaker.

This addresses one of the bugs demonstrated by issue 2 in #3273.
Merge pull request #3289 from hjdivad/fix-3273-guid-as-tiebreaker

`Ember.computed.sort` fallback to guids.
`ReduceComputed` groups changed properties.

This is mostly important for sorting when items are changed via `setProperties`
instead of a sequence of `set`s.
fix nested yield
Merge pull request #3290 from hjdivad/array-computed-sort-via-sortProperties

`ReduceComputed` groups changed properties.
Typos and whitespace
IE indexOf fix again, this time without breaking every other browser
Merge pull request #3291 from lukemelia/ie-index-of-fix-moar-compat

IE indexOf fix again, this time without breaking every other browser