Enhancement: support <changeset> from a loaded .osm file

[brycenesbitt]

When I have a script prepare a changeset for human review in JOSM, it would be great if I could supply default changeset information also:

<?xml version='1.0' encoding='UTF-8'?>
<osm version='0.6' generator='example'>
<changeset>
 <tag k="source" v="http://www.example.org/"/>
 <tag k="bot" v="yes"/>
 <tag k="note" v="Import of examples from example.org"/>
</changeset>
<node action='add' id='-1' lat='29.757632' lon='-95.397670'>
    <tag k='amenity' v='toilet'/>
 </node>
</osm>

And have that information appear as the settings for any subsequent upload.

[Don-vip]

Closed as duplicate of #8149.