Polynomial reconstruction in SharpClaw

This PR adds a routine for polynomial based reconstruction in SharpClaw. In detail,

 - 4th and 6th order Polynomial reconstrcution
 - 8th and 10th order reconstruction are also included but have not been fully tested yet
 - renames "weno_order" to "interpolation_order"
 - deallocate calls for WENO5 and Poly_comp
 - sets number of ghost cells for either Weno or Poly in solver
 - documentation

This should say

> From 5th to 17th order (odd) for WENO reconstruction and from 4th to 10th order (even) for piecewise polynomial reconstruction.