JXTemplate and FOM

[Christopher Oliver]

I'd like to change JXTemplate to use a subset of the FOM, namely by 
providing a variable "cocoon" with the following properties:

- request
- session
- context
- continuation
Each of these would be a reference to the corresponding FOM object. This 
will unify the object model of the controller and view.

I will deprecate the existing "request", "response", "session", 
"context" (which point at org.apache.cocoon.environment Java objects) 
and "continuation" variables but continue to support them.

Any objections?