Some KML options should be per content type

This is partly related to "Allow for icons in GE to be altered" (http://drupal.org/node/82725).

As well as icon definitions on a per-node basis, some other features (OK, at least one) makes sense to appear in the content types config screens.

In the same way as the location.module places 'Location' fieldset atop each content type screen (with "Number of locations", "Location weight", etc, etc) these settings would be better placed on a per-content type:

- Node display
- Highlight placemark URL
- Normal placemark URL

(Second two are added as part of http://drupal.org/node/82725 patch).

We want Node display on a per content type basis, because some of our content types (describing various trails) have KMZ files embedded in the nodes themselves, so pointing to the node location alone is not what we want here. On images though, for example, it does make sense.