shortern constructor reference resolving and prototype wiring

[yangjh]

change return new jQuery.fn.init( selector, context );
to return new init( selector, context ); so that reference path is shorten

change jQuery.fn = jQuery.prototype = {
to jQuery.fn = init.prototype = {

remove jQuery.fn.init member make the core smaller

remove confusing line jQuery.fn.init.prototype = jQuery.fn;

rerun all test case passed, rerun all speed test, performance almost the same though, but not slower
benefit: less ninja-ish

[davidmurdoch]

I thought JS ninjas were a good thing.

Qk <---- ninja (turn your head sideways)

[dmethvin]

Since there isn't a ticket addressed by this pull request and it doesn't solve a problem, I'm going to close it. Code cleanup and simplification is a good idea but I'd prefer to do it in the context of other work such as bug fixes in the same region.