Next version of remote control API

[akks]

Since we have started to change remote control functions r5872 r5845 r5837 , the version of Remote control API should be increased.

But before doing this, we may need to implement some minor remote control enchancements. I propose to discuss all of them here.

I was asked to add some functionality by CupIvan, author and maintaner of one of Russian validators ​http://osm.cupivan.ru but it needs discussion.

1. Allow "noconfirm" option to add_tags parameter - do not show confirmation dialog at all (+one more security permission ? )

2. Allow separate request to return JOSM version (to check supporting extra fuctionality). Do we want to allow getting some more JOSM info, like installed plugins ?

3. Allow to add changeset tags that indicate usin the specific validator/web tool by remote request (changeset_tags parameter?) , related to #8149

-- From me:

4. Document, enchance and use zoom_mode parameter in all possible commands (see also #5669)

5. (most crazy) Support opening remote file with preferences ​http://josm.openstreetmap.de/wiki/Help/Preferences/ImportExport or execute configuration xml script sent in POST request if the user really agree with it. This could help to install plugins, specify imagery sources customize toolbars/styles/presets for team work.

But there is possible security issue - for now, arbitrary JS execution is allowed and JS has full access to Java API. The code checker may be added to restrict the configuration, maybe forbid JS execution more complex than ${a==2 && b==3}.

We could implement the steps independently, when reaching an agreement which ones to add.