Convert Global CSKILL, CCSKILL from ChooseResultActor to ChooseSelectionActor
(adds type safety)

Issue#: CODE-1902


git-svn-id: svn+ssh://svn.code.sf.net/p/pcgen/code/Trunk@22818 ef53c05b-3124-4d59-ae7d-fe3273f42be7