[Webtest] [dev] refactoring

[Paul King]

Dierk Koenig wrote:
> The internal state of a step consists of 
> - information that only this step cares about,
>   e.g. its attributes
> - information that is common for all steps
>   and is of 'read only' nature, e.g. the testSpec
> - information that is shared, handed over from step
>   to step, and is of 'read/write' nature.
> The latter is called the context and extracted into
> the Context class.
> This is the logic of the separation and it is reflected in the
> current object design.

I mostly like the current objects (add Configuration to the above list)
and think keeping them (perhaps with some refactoring) would be useful.
However we shouldn't need to do both of the following:

step.setContext(context)
step.doExecute(context)

Getting rid of one or the other would be good.

Paul.