get rid of the Copy trait for K and V

[yegor256]

Somehow Vec and HashMap work with keys and values that don't implement Copy. We should do the same. I'm not sure exactly how this can be done, but it should be possible.

[WiebeCnossen]

I am not sure this would have great value for micromap: it is meant to use the stack whereas Vec and HashMap are intended to use the heap. Using micromap with types that do not implement Copy would probably be an unusual case.

Also depending on how far you want to take this issue (concretely: remove Clone as well), this would have an impact on the current API as e.g. .into_iter(&self) really cannot do without this.

[yegor256]

@WiebeCnossen I'm not really an expert in this area. Help me understand. Now, when we put a pair into the array, we do memcpy. If we use Clone, we will put pointers into our array? Is this your concern?

[yegor256]

we don't use Copy anymore