New Report Helper function

Hello,

When we do reporting in OpenObject/ERP we often have to do the same stuff. With time we had made a collection of helper. I think we are probably not alone. It will be great to have the list of standard report helper (ex: formatLang) augmented and be available inside the report or the RML. Some of these helper may even have their place on the tools helpers. I think It would be great to make a list of the helper the community want to have inside the framework.

Here are the helper we commonly use

A memoizer helper with the following signatures :
    def memoize(self, key, val):
    def remember(self, key):
    def forget(self):

A Increment manager helper (for cumulated computation) with the following signatures :
    def incr_total(self, column, val) :
    def reset_total(self, column) :
    def get_total(self, column) :

A formatting helper with the following signatures :
    def elipsis(self, string, maxlen) # if a string is to long for a column it will cut the string and set … and is end. (ref: Custom...)
    def translit(self, basestring) # translitarate all non ascii chars