Rework preference pages
More preferences work
Merge remote-tracking branch 'upstream/master' into fixflow-kepler

Conflicts:
	org.eclipse.bpmn2.modeler.core/src/org/eclipse/bpmn2/modeler/core/preferences/Bpmn2Preferences.java
	org.eclipse.bpmn2.modeler.ui/src/org/eclipse/bpmn2/modeler/ui/editor/BPMN2Editor.java