Abstracted Stencil DSL

[muellch]

Finite difference stencils in space and time dimensions can be expressed in more abstract ways than is possible in the current stencil DSL.
We have to estimate if there is a performance benefit to be gained by introducing a higher level more abstract Stencil DSL that does transformations before compiling down to our current stencil DSL.

Roughly this higher level DSL could have nouns as abstract as "2nd order centered finite difference stencil of the 2nd derivative in 3 dimensions".