jquery.makeCollapsible: move helper functions to the outer scope

They do not directly use any variables defined inside
$.fn.makeCollapsible (although they used to), so let's move them to
the appropriate place.

Also indent the body of the immediately-invoked wrapper function.

Change-Id: I3d5f33b4a3ed8bd72c5f55c4d9fa545e4f3bd8c4
Merge "jquery.makeCollapsible: move helper functions to the outer scope"