Dof Number Ordering

[friedmud]

Currently dof number ordering for higher order variables on the same dof object are like this:

var_0_comp_0 var_0_comp_1 var_0_comp_2 var_1_comp_0 var_1_comp_1 var_1_comp_2

This is inefficient if you want to treat all of those variables together. For instance, if you want to multiply all of the comp_0 components by phi_0... you can't do that in a contiguous, vectorizable way.

Here is some background and discussion on this:

https://sourceforge.net/p/libmesh/mailman/libmesh-devel/thread/CAFfxPjqrmX_pHCZp%2B7sMGZR%2BYxQ%2B5nNqfVCVgzunrCvnd1TM1Q%40mail.gmail.com/#msg36649810

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