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.

<intent-filter>
    <action android:name="android.intent.action.SEND" />
    <category android:name="android.intent.category.DEFAULT" />
    <data android:mimeType="*/*" />
</intent-filter>