Add optionally faster sessions which don't hit the backed each time you ...

...get or set a variable

Every time you get or set, a call to retrieve or flush is made, which can be expensive. This change makes it possible to avoid hitting the back end each time.

This is a backward compatible change. Users need to declare they want a "fast" session and the chosen back end needs to have implemented a ->fast method for it to work. The user is responsible for saving sessions.

By way of example, Dancer::Session::ElasticSearch 1.003 implements the necessary changes at the session engine end of things.

Ta

Robbie