Fix inconsistent behaviour of feature version filter when using the CLI

[clausnagel]

The feature version filter behaves differently for different CLI commands. To reproduce the following examples, load a small dataset into an empty database and terminate all features right afterwards.

1. export -H localhost -u user -p password -d db -o test.gml

   When doing a CityGML export from the database with the above command, no features will be exported because the
   command only works on non-terminated features by default.

2. export -H localhost -u user -p password -d db -o test.gml -t Building

   When changing the command by adding a filter (like the feature type filter above), the behaviour changes. The command
   does not use a default feature version filter anymore and, thus, all buildings are exported. If you only want to export non-
   terminated features in this case, you must explicitly add -r latest.

3. export-vis -H localhost -u user -p password -d db -o test.kml -D collada -l halod

   A simple visualization export behaves like the first CityGML export example. Only non-terminated feature get exported.

4. export-vis -H localhost -u user -p password -d db -o test.kml -D collada -l halod -t Building

   Adding another filter does not change the behaviour - again only non-terminated features are exported. Thus, export and
   export-vis behave differently.

Note that the delete command behaves like the export command. The different behaviours of the commands are at least unexpected. This PR proposes that all commands should behave the same and use a default feature version filter for non-terminated features.