fix disableCopyMove for empty arguments

This MR adds a regression test with the (in my opinion) expected behaviour and fixes the compilation failure in case of an empty argument list for libg++7(+) (see #96 (closed) ).

This changes the previous behaviour so that now disableCopyMove is valid in case of an empty argument list.
Also removed is the check for is_same since is_base_of also check if class types are the same (see cppreference).

@carsten.graeser Could you please take a look since you are the original author.

edit: removed the mention of possible UB. I confused some standard wording.