Use CollectionView's layerId rather than guid in contentIndexForLayerId.

Previously, use of guid meant CollectionView's could not have a custom
layerId set.
Merge pull request #1185 from sproutcore/team/fairbanksg/collection-view-layer-id

Use CollectionView's layerId rather than guid in contentIndexForLayerId.
Adds much more descriptive documentation for configuring SC.PickerPanes including the use of new constants SC.POSITION_RIGHT, SC.POSITION_LEFT, SC.POSITION_TOP & SC.POSITION_BOTTOM to make the values of preferMatrix more clear.
Privatizes pointer layout array used internally by SC.PickerPane. Also tidies code a bit.
Sets the windowPadding of SC.PickerPane to default value once rather than checking it each time.
Adds some debug-mode only developer support to prevent the easy mistake of using .append(anchor) with a picker pane instead of .popup(anchor).
Improves view event documentation. Fixes a typo which was conveying some bad information.
Have SC.ScrollView#scrollToRect prefer the top/left of the rect.

Previously, the top/left side would be scrolled into view first, then the
bottom/right side. This resulted in the bottom right being in view if the
rect was larger than the viewport.

Now scroll the bottom/right first, so the top/left is in view in this case.
Fixes a number of issues with SC.SplitView:

- Adds layoutDirection property and class-name to SplitDividerView. Hooks up propagation from parent SplitView.
- Fixes bug where SplitView's class-names would update incorrectly when layoutDirection changed. (Previous class was not being removed.)
- Fixes CSS bug where selector hierarchies were insufficiently specific, causing a misapplication of styles in nested SplitViews with different layoutDirections.
- Includes unit tests.
Revert "Swaps out @jlaxson's SC.SegmentedView#shouldAutoResize for @publickeating's suggestion that the behavior be mediated by setting shouldHandleOverflow to NO. (There is currently no way to prevent resizing in a static-width segmented view with shouldHandleOverflow: NO; if that's a need, it shouldn't be hard to implement.)"

This reverts commit 3f9128971e9ce7da0b97221a3dbd71975a90fb7c.
Updates README with some better links and new verbiage.
Adds an escapeForCSS method to SC.String.

The '.' and ':' characters are valid in HTML ids, but cannot be used in
a jQuery selector without being escaped. I added a method to escape a
string for use as a jQuery selector.
Renames `escapeForCss` to the less-nice but more-precise `escapeCssIdForSelector`.
Tiny bit of whitespace clean up.
Removes forcing the prototype layout onto all child views which is redundant and prevents child views from having their own layout.
Prevents SC.CollectionView from pooling views that don't have a layout (i.e. static views). Fixes failing unit test.
JSHint cleanup.
Adds unit tests verifying the reset of an SC.Store.
Fixes bug that doesn't clear nested records from a store reset (fixes failing unit test in previous commit).
Fixes the debug only SC.PickerPane message. This helps developers avoid confusion if accidentally calling append instead of popup on a picker pane.