new feature: retained layouts, automatically styled
update child layout specs to test for reapply
OMG!  Removed motion_kit_id - element_ids are now specific to the layout.  This design makes things like 'get' much easier, but 'get(in:)' has been removed

get(:id) no longer builds the layout, but that could change
remove(:view) no longer removes subviews of get(:view) from the layout
gave a bunch of specs better names
removed the _root/@root stuff - no longer needed with simplified 'get' and element_ids
README correction
in a constraints block and in frame helpers, use the 'view' not the layout
oh, never implemented hugging and content compression helpers
refactor the method that calls the 'style' method.  renamed to 'style_and_context', which also calls the block within the context (so style methods and blocks are handled the same way
better way to check for a context
a layouts parent *can* change, it turns out
how did this get through?
Merge branch 'master' into feature/child_layouts

Conflicts:
	lib/motion-kit-ios/layouts/uiview_layout_constraints.rb
	lib/motion-kit-osx/layouts/nsview_layout_constraints.rb
added specs for NSTableView (adding NSTableColumn)
Merge branch 'master' into feature/child_layouts