Update jquery.hashchange.js

[smithxxl]

Allow a change or reset to another previous hash so hashchange can fire or not fire when needed.

I didn't change the dist code, just the source. I'm sure there is a better way, but this was a quick fix for what I needed. I was trying to force a hashchange to run again. So my solution was to clear out the previous hash and then trigger.

$(window).hashchange("prevHash", "");
$(window).trigger("hashchange");