feat(Diagram): print instantiation errors to console

This commit adds debug output to the developer console.

This makes failures in instantiation / module configuration more obvious
to developers and sophisticated users.
fix(navigation): attach modules to svg

Instead of attaching to the viewport we attach ourselfs to the svg in
order to receive all relevant interaction events.

This fixes problems where the diagram cannot be scrolled, zoomed or
touched outside the bounding box of existing elements.

Related to #57
fix(core/EventBus): print out error stack on listener failure
fix(selection): do not select connections

This restores the old behavior (only shapes can be selected) until we
are able to properly select connections, too.

Related to #57