Fix test failures and simplify magic methods
Fix test failures and simplify magic methods

- move `copy()` to `FunctionSet.Vector`
- add apply variants to `one` and `zero`
- remove unreachable cases from `__rop__` methods
- return out in lincomb and multiply

kohr-h/odl,aringh/odl,kohr-h/odl,aringh/odl,odlgroup/odl,odlgroup/odl