FIX: Hierarchy markOpened incorrectly applying

Moved call to `markingClasses()` to after resolution of the nodes children has happened. This fixes the jstree-open applying before the tree has been checked.

Previously nodes with children would get `jstree-open` applied before checking for if the tree is open or not has completed.

Also changed `$node_threshold_total` from 50 to 30, as it's changed to 30 multiple times in the file. This should should be refactored to be more consistently calling the `$node_threshold_total`.

LeftAndMain was missing an argument with it's call to `getChildrenAsUL()`, this has been added though it shouldn't be affecting the `markOpened()` call.
Um... I think it's because I rebased, after making the initial pull request.
I'll need to have a look at some git docs, to work out how to remove this.