fuzzy matching

Hi,

so here is my shot at fuzzy search. I hope I don`t embarrass myself... :)

The idea is similar to what you know from the quick panel in ST. Here is an example: The queries `nor20`, `n2013`, `NordAmid`, and `norld3frs` all match the string `Nordland 2013 - Amid Fears of Releases`. There are three criteria for a match:
-  all the letters of the query are in the string
-  the letters in the query are in the same order in the string
- there is at least a sequence of 3 correctly matched letters (the user can change this with the seq argument)

Matches are ranked based on two criteria:
- sequence of characters (e.g. for query `nor`, `nor` is better then `nxoxr`)
- earlier matches are better (e.g. for query `nor`, `xnor` is better then `xxnor`)

The import function is `fuzzy_search`, which takes two required and three optional arguments. 
- `query`: search string
- elements: list of strings, dictionaries, tulpes, or lists
- (optional) `key`: function to access string element in dictionaries, tulpes, or lists
- (optional) `rank`: rank the elements in the return list by quality of match (currently not supported)
- (optional) `seq`: minimum sequence of characters to match

`fuzzy_search` returns a ranked list of elements that matches the query.

`key` has to be specified if `elements` is not a list of strings and `key(elements[i])` has to return a string for every element in the list `elements`.

I am sure this can be optimized performance wise but it's pretty fast in my tests with a list of over 2000 elements and `seq=3`. There is also an small example at the bottom of the code (commented out). By they way you can also use this to directly filter a list of feedback dictionaries with `key = lambda x: '%s - %s' % (x['title'], x['subtitle']` (in this case the search would be based on a string 'title - subtitle')

Another thing is that you have to feedback a random uid to preserve the ranking. I think it would be great to add an option `random` to `alp.feedback`, which assigns uses a random uid and set this option to `False` by default. [Here](http://www.alfredforum.com/topic/1332-alfred-v2-not-honoring-xml-order-in-script-filter/?p=6544) are details about this.

Let me know if you have questions!