[IMP] ir_actions: server action: evaluation context preparation is done in
its own method, to ease the inheritance and to allow other modules to
add new items in the evaluation context.
[FIX] ir_actions: typo in comments
[MERGE] [IMP] ir_actions: server action: the context used to evaluate python code (condition, code server action) is prepared in its own method. This eases the inheritance process and allow s other modules to add new items in the evaluation context. An example of use is to add the request object in the website module, allowing some server action to be accessible through the website front-end.