Enhanced FiniteStrainMultiPlasticity so it can do rotations to allow transversely-isotropic yield functions to be more easily defined in just one frame.

Changed all weak_plane_tensile tests to use UserObjects.
Deprecated FiniteStrainWeakPlaneTensile Material class.
FiniteStrainWeakPlaneShear Material deprecated in favour of UserObject version.

Also a Gaussian hardening version added with a test

Fixes #3878
Merge pull request #3935 from WilkAndy/wp_to_multi_3878

Wp to multi 3878
Merge commit '8eeaea8fff10ffebc9c2530fa14ab29c7409e362'