"require server load" config var

[donundeen]

sometimes a widget basically requires running on the server to execute some part of itself. And sometimes that requires a bunch of other dependancy widgets to run. plus the overhead of loading up the entity itself. So if several nodes are doing this, we don't want to run all that code more than once.

So the entity should ask all the widgets, when it runs client-side, "Do you need a server-side load too?" If any of them say yes, it will run the entity server-side, just once.