Fix parsing of custom namespace routes. Transform class names, removing dashes and capitalizing each word/route part so a route path of `widgets/recent-posts` becomes a collection with the name `WidgetsRecentPosts`. Correct parent route part when routes are longer than expected, reversing parse direction.
Props westonruter, jazbek, adamsilverstein, jnylen0.
Merges [40074] and [40109] to the 4.7 branch.
Fixes#39561.
git-svn-id: https://develop.svn.wordpress.org/branches/4.7@40117 602fd350-edb4-49c9-b593-d223f7449a82
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