GeoCoding: Don't override identifier type in set_data

[janezd]

Issue

Fixes #179.

In set_data, we have

        self.openContext(data)
        self.region_attr_changed()

region_attr_changed() is the callback for combo with the attribute, and it includes a heuristic for setting the identifier type, thus overriding the value from the context.

Besides, it calls commit, which is ugly - set_data was not calling commit on it's own because it called region_attr_changed, which does it. Forget about proper implementation of auto_commit...

Description of changes

Reorganize the callbacks, and use heuristics for setting the type only if type is not recovered from the context (i.e., when no context matches).

Somebody should write tests for this. If nobody does it before the next release, we can still accept the PR as it is (if it's correct), because the widget is rather untested anyway.

Includes

• Code changes
• Tests
• Documentation