core (common): improved flexibility of jid selector: - JidSelector can now display a custom set of jids, using the new `to_show` property, see comments for details. - a new "implicit_update" property can be set to False (it's True by default) to avoid the automatic "update" on instance initiation. If unset, use must call "update" explicitly.

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^*android/
^*libs/
^*bin/
^*service/