NEW "Show children as list" tree context action

Allows for easier navigation between tree and list,
particularly if a node has many children nodes
(since it doesn't require expanding that node).

Uses a new 'ss-tabs-force-active' class on the tabset
to enforce the correct view state. This also fixes an issue
where you couldn't link to a list view directly via URL.

Conflicts:
	javascript/CMSMain.Tree.js
	javascript/lang/en_US.js
	templates/Includes/CMSMain_TreeView.ss
	templates/Includes/CMSPagesController_Content.ss
NEW Set correct ParentID when creating page from list view
NEW SiteTree->updateCmsListViewForm() to modify the displayed list