jQuery.Preload 1.0

This is an advanced multi-functional preloader, that has 4 modes integrated.
Each mode suits a different, common situation.
The modes are: 

* URL: Preload a JS array of static URLs.
  	related settings: 
		+ base: This string is prepended to each URL in the array. 
		+ ext: This string is appended to the end of each URL in the array. 
* Rollover: Preload based on DOM images, slightly modifying their src.
 	Can be used for rollovers, or for image-thumb.
  	related settings: 
		+ find: String or regex that matches part of the srcs. 
		+ replace: Replacement to the matched part, to generate the alternate URL. 
* Placeholder : Take regular images and set a placeholder image while they load. Show each original image when fully loaded. Allows sequential loading with a threshold.
  	related settings: 
		+ placeholder: URL of the temporal image shown while loading. 
		+ notFound: Optional image to show if a given image failed to load. 
* Link: Preload the images that appear in the href of the given links.
  	related settings: none. 

The plugin also provides 3 callbacks to interact with the image URLs during the preloading process. The callbacks get a hash of data, with details of the related image and global information.
The callbacks are: 

* onRequest: Called when requesting a new image. 
* onComplete: Called when a request is complete(loaded or failed). 
* onFinish: Called when all images are fully preloaded. 

The hash of data received by the callbacks, contains the following information: 

* loaded: how many images were preloaded successfully. 
* failed: how many images failed the preloading. 
* next: 0-based index of the next image to preload. 
* done: amount of preloaded images ( loaded + failed ). 
* found: whether the last image could be preloaded or not. 
* total: amount of images to preload overall. 
* image: URL of the related image. 
* original: The original source related to this image. 

There's also a threshold setting, that determines how many images are preloaded simultaneously, it is 1 by default.
Note that threshold and the callbacks, are not related to any mode, and can be useful for any of them.