RotatingSymmetry180: fix 4scalar alias, support vectors of grid functions, add test thorn

RotatingSymmetry180: fix 4scalar tensortypealias detection

RotatingSymmetry180: support vectors of tensor grid functions

This adds support for constructs like:

CCTK_REAL tensor[42] tensortype="dd_symm" { txx, txy, txz, tyy, tyz, tzz } "some symmetric tensor"

and special code to handle the vel[3] construct used by HydroBase

RotatingSymmetry180: reduce number of compiler warnings

there are some left, of the type:

void **

being an incompatible pointer with

const void * const void *

which seems to be due to C99 being uwilling to accept some non-const objects in place of const ones.

TestRotatingSymmetry180: execrise RotatingSymmetry180

TestRotatingSymmetry180: add test