StaticImports are copied into new package instance

During the knowledge base process, constructed KnowledgePackages are cloned and then also manually copied into new instances. During that merge some information losts, e.g. record of static imports of function.

This pull request fixes the merge function by copying also the static imports. The functionality is required for developers (as me) programatically dealing with knowledge packages inside of knowledge base.

If the pull request will be approved I will publish another to merge it into upcoming version of 6.2.x