Removed geometry from previous document if GeoJSON_clone is set.

This makes it possible to attach documents to existing geometries.
Displayed link instead of just a bold document id.

Every once in a while it is nice to know where to clone from.
Reviewed geometry selection logic in upload.html.

The key conceptual error has been that GeoJSON_clone being identical to the
document id does not necessarily imply that the geometry is new; It might as
well come from the previous document version. In this case GeoJSON_clone is set
to its own document id, however, feature.items is missing its own id and the
script throws an error.
I moved the entire id vs. GeoJSON_clone being undefined or the id itself etc.
etc. into $("#reduce [name='show']").click() and made show_geometry() working
with feature.items[<some id>] being defined or not, because this is actually
what it boils down to. That should ease maintenance.
Removed two redundant ifs in upload.html.

feature[f].items is always defined and so is feature[f].items[id].shape.
Expanded field collection RegExp in upload.html.

This way, unquoted field names with spaces are left unchanged, e.g.
'F.I.E.L.D'.nested object <-> {"F.I.E.L.D":{"nested object:..}}
should work.
Leading/trailing spaces are not stripped, because it isn't that important.