_requireExtension: order managment

[jjagielka]

Expected and Actual Behavior

fancytree/src/jquery.fancytree.js

Line 2432 in a55bb6e

before = !!before;

Function _requireExtension should treat null passed as before parameter as order not important, but !!before turns null to false and therefore this is treated as after.

I wonder why this line was added, as it breaks the expected behavior.