I attach in vectors90.patch a patch to support groups of vectors the same way reflectionsymmetry does. The parfile tests this with Luke Robert's thorn. It requires access to Zelmani. Please ignore the no_local_reductions90.patch file as I only uploaded that one accidentally.
Please comment on whether this is an acceptable way of implementing the functionality (or whether we want a separate variable "tensorcomponent" rather than all the "/ tensorlength").
I added a patch to correct interpolation in rotatingsymmetry90, before it would have failed (triggered an assert) if multiple vector components were interpolated at the same time. There is a very helpful comment in the code just above the assert (interpolate.c lin 886) , many thanks to whoever put the comment there.
bump priority since people are actually hit by this and I am no longer sure if the assert() catches all usage cases (eg it might not catch the case where only vel is interpolated). The bug manifests itself as always interpolating the x component of vel even if vel is requested.
A pull request for RotatingSymmetry180 is here the pull request also fixes a bug that made the "4scalar" tensortype unusable b/c the type was spelled as "4-scalar" in interpolate.c (it is spelled "4scalar" in RotatingSymmetry90 and in rotatingsymmetry180.c).
Unless objected I will apply this after 2019-05-14.