Eclipse Sirius 6.4.1

This is service release to fix two issues which were not detected in time for 6.4.0. The issues only impact a new API which was introduced in 6.4.0 (Bug 563117 - Copy format to existing/new diagram based on source to target semantic elements mapping).

Users who want to use this specific feature are encouraged to move to 6.4.1, but otherwise the bugs has zero impact on the rest of Sirius.