Problem with clusterer2.js cluster bounds

This issue is not really regarding the gmap module but the Clusterer2.js file so it isn't just directed at 5.x-1.x-dev.

Hard to explain but:
I have found in some cases when your map covers an area that wraps around the point where latitude -180 & latitude 180 meet the Clusterer can get mixed up and set the grid squares in the wrong places, resulting in it not finding any markers within the grid squares and therefore not clustering any of your markers.

This would result in clusters sometimes working and sometimes not depending on the bounds of your gmap.

This patch fixes this issue for me.

If anyone else has been having this issue, try the patch and see if it helps.

Also, if people can confirm this fixes the issue it might be good to get it back to Jef Poskanzer to update his code.