Improved overall readability of map.html javascript.

I moved event hook initialization into $(document).ready(), i.e. one-off global
scope, and threw in a few empty lines between function blocks.
Enabled username/password inputs for pull replication.

The central database is very very very very very secure, so noone is allowed to
read its delicate content!!! I also re-arranged the script bits a little.
Converted doc.range object back to its string representation.

.. in _list/export. Not even my beloved Quantum GIS is able to handle object
properties even the slightest bit.
Added 'download' query parameter to _list/export.

Because if I went through the effort of copying a lengthy url into the browser
address bar, I do not want to end up with a file in the downloads folder.
Removed (obviously) unused parameter to translate_url().
Removed URI encoding from download link.

I like how the URL looks clean and human-readable and ignore the fact that this
might be unsafe!!!
Added document revision to _view/geojson.
Added 'include_revision' query parameter to _list/export.

It is slightly misleading because it does not imply that doc._id is also
included. However it probably takes a couple of milliseconds to realize that a
revision with out an id is silly.
Changed bool query parameter syntax in _list/export.

Because '=true' is way too long for my taste. This looks nicer.
Added 'fields' query parameter to _list/export.

Syntax reads as in 'Maßnahme:Fläche' and an empty string indicating no fields
is also accepted.
Added 'include_geojson_id' query parameter to _list/export.

This should be all now, enough with the parameters already. Geometry IDs should
come in handy as soon as import/export of ghastly XML spreadsheets is ready.
Removed var filename being used only once.
Simplified 'download' query string.
Implemented client-side use of _list/export query parameters.