Most of the cached attributes invalidated by Browser._changed() were
based on the response, so it makes more sense to invalidate them from
Browser._setResponse. This means that Browser.goBack() now invalidates
these caches, so subsequent uses of methods such as Browser.getLink()
work properly.
_req_content_type is an exception to this: this is a property of the
request, set by Browser.post(), and it still makes sense to clear this
in Browser._preparedRequest().
Most of the cached attributes invalidated by Browser._changed() were based on the response, so it makes more sense to invalidate them from Browser._setResponse. This means that Browser.goBack() now invalidates these caches, so subsequent uses of methods such as Browser.getLink() work properly.
_req_content_type is an exception to this: this is a property of the request, set by Browser.post(), and it still makes sense to clear this in Browser._preparedRequest().
Fixes #83.