Add error message if required plugins are not installed

[alterNERDtive]

I’m already waiting to make sure that EDDI is initialized; way to go would be to add a timeout there which sadly is a bit finicky unless I move the entire thing to plugin code.

With the intended removal of bindED from the profiles package (#143) I’ll need to do a similar thing with that.

I’ll have to look into possible ways to detect the presence or absence of the neutron router plugin, too, since I’m probably not going to replace that anytime soon.