Control automatic node rendering

[u-874]

Added functionality to pause and reenable automatic node rendering. This
feature is useful when many changes to the tree (its nodes) are made at
once (e.g. initial loading) and rendering slows down the process. I was
able to reduce the initial loading time of 30000 nodes from nearly
endless (I stopped after 20 minutes) to about 30 seconds.

TLDR:

fancytree.setRenderingPaused(true);

// Add thousands of nodes to the tree
// ...

fancytree.setRenderingPaused(false);
fancytree.render();

[u-874]

Fixed merge error

[u-874]

Fixed lint error.

[mar10]

Thanks, I will look into it if I find some time.
Anyway it would be good to have tests for it (benchmarks) so we can compare different approaches.
Dynatree had something like tree.enableUpdate(enable) that returned the previous state, which makes it easier to restore in nested calls. It also forced a redraw on enableUpdate(true).
See http://wwwendt.de/tech/dynatree/doc/dynatree-doc.html

Instead (or additionally) to suppress rendering, we should also benchmark performance, when the tree root element is detached while adding nodes (see https://api.jquery.com/detach/)

[mar10]

Closing in favor of a general feature request - #607
thanks!

[mar10]

@u-874 could you explain a bit, what operations were slow?
Did you use the table table extension or some other plugins?
How did you add nodes, and how many?