Feature request: flag to suppress display() and pprint() of "empty" containers

[qtothec]

In the interest of easier modeler troubleshooting, display() and pprint() should have the ability to suppress the output of Blocks/IndexedComponents that are not activated.

That is, not only not display the child components that are not active, but not show the container entry at all.

[jsiirola]

Note that #839 points out that display() outputs deactivated blocks in a manner that makes it difficult to see that the blocks were deactivated.