- Fixed bug where the format chosen for exporting images was always returning null, preventing the user from exporting any images except for elevations.
- Added more file filters to the Swing FileChooser and added a hashmap for matching those extensions to mime types

It would be great though if there was another example of how to make these export functions used the locally cached map tiles instead of requesting them repeatedly from a WMS endpoint.  I know the elevations are exported by reading local data, but for some reason the Image capture functions don't seem to be able to read / access / or modify a local cache and default to always making a new request from external servers.