Enforce stricter recyling rules

[sebffischer]

1. When assigning to a vector like l[s] = r we need to perform the length check before starting the assignment in case we directly mutate l, as we might otherwise get a corrupted left hand side.. This length check is possibly expensive.
   if the left hand side is cloned anyway (in case there is more than one reference to the internal vector data) we could just start clone the data and overwrite it. When we then afterwards figure out that the lhs and rhs iterator were not recyclable the result can just be discarded. For now I have just implemented a relatively naive solution.
2. When conducting vectorized operations such as +, we can alyways just start the computation. It one if the iterators is not yet exhausted after iterating, we can then throw an error and discard the result.

TODOs:

• for scenario (2): Handle the case where either the lhs or rhs iterator has length 1.
• Ensure that the issues / suggestions listed here: Stricter recycling rules #98 are all covered
• Integrate the relevant tests from here: Feat/coerce #155
• unify the rep.rs recycling tests with the reptype.rs recycling tests