[FEATURE] Redirect to Shortcut target page

Redirect directly to the target page in Frontend, if the accessed page
is of type Shortcut and accessed directly via its URL.

Change-Id: I4199cb8c89d6dc5a21dac6f3cd03051245880bd8
Resolves: #28322
Releases: 4.6
Reviewed-on: http://review.typo3.org/3398
Reviewed-by: Philipp Gampe
Tested-by: Philipp Gampe
Reviewed-by: Kay Strobach
Tested-by: Kay Strobach
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind
Reviewed-by: Christian Kuhn
Reviewed-by: Susanne Moog
Tested-by: Susanne Moog