This reverts commit 7fd82fef.
The change breaks lots of dependent code (reference-to-stack).

They all use the same implementation now.

René Fritze authored 4 years ago and Dr. Felix Tobias Schindler committed 4 years ago

hiding functions for "wrong" args only makes sense
if there are alternatives

Note: this is the cherry-picked variant of the just reverted commit without
create() and zeros_like() in matrix.hh, there are alternatives in
vector.hh.

This reverts commit 28bc70ca.