Improve accessibility to transition preferences

[SimonEit]

For eclipse expert users it is clear that properties refer to a single element (hence the properties view) and preferences refer to the whole project.

This is not clear for users on beginner levels. This results in difficulties to execute a task like "change the routing style for all transitions" for this user group.

Recommendation is to add a "Global Preferences" link on the properties view, that opens the preference page "Diagram Appearance" on click.

Mockup: