Force re-rendering of all mounted Reagent components. This is probably only useful in a development environment, when you want to update components in response to some dynamic changes to code. Note that force-update-all may not update root components. This happens if a component 'foo' is mounted with `(render [foo])` (since functions are passed by value, and not by reference, in ClojureScript). To get around this you'll have to introduce a layer of indirection, for example by using `(render [#'foo])` instead.