phrase engine: new FxPhraseTreeNode#createRootNode variant where the phrase object can be passed

git-svn-id: http://svn.flexive.org/repository/flexive/trunk@3007 d35d4baa-7912-0410-b0ae-edacad209e15
phrase engine: bugfix in saveTreeNode

git-svn-id: http://svn.flexive.org/repository/flexive/trunk@3008 d35d4baa-7912-0410-b0ae-edacad209e15
phrase engine: bugfix loadPhraseTree

git-svn-id: http://svn.flexive.org/repository/flexive/trunk@3009 d35d4baa-7912-0410-b0ae-edacad209e15