Solves 1191, 1192 & concludes 1187.

-> now the subcomponents of a library reference component cannot be seen outside of the library itself (in the model navigator only)
-> opening the library reference component directly leads to its definition in the library
Consequently, only one editor on a library reference component can exist and it is now impossible to get incoherences

Bonus: a library reference component has a slightly grayed out icon to indicate it refers to a library element


refs 1191