Look-up mated connectors before mate processing

[kvid]

The code processing mates used a mix of repeated connector look-ups and local connector variables, and one variable was used before it was assigned the correct value.

This error was detected when investigating the #355 bug report.

The local connector variables are now both assigned initially when processing each mate, and used instead of repeated connector look-ups.

The same code section also has an unfortunate side-effect (not yet reported by any user) that is planned to be fixed as a separate commit into this PR.