Parameter copy sanity checks.

Parameter copy sanity checks.

Don't copy parameters is they're already present in the destination.
Return error if an attempt is made to copy different parameters to
destination. Update documentation.

If key type is not initialised return missing parameters

RT#4149

Reviewed-by: Richard Levitte <levitte@openssl.org>
(cherry picked from commit f72f00d49549c6620d7101f5e9bf7963da6df9ee)