GME v0.7.2

* Bug fixes:
 - GPX files exported from GME should now work when imported into Geocaching.com's "caches along a route" feature.
 - tileUrl for Hill Shading fixed (due to server change).
 - Better handling of caches with special international characters in their names or waypoints (multi-byte Unicode). These should now work properly for clicking-though to display on the big map, or dragging and dropping.  Obscure side-effect: when cache information is dragged to another app as a `data:` URI, the data has to be URI-decoded after base64 decoding.
 - Improved keypress event handling to allow searching by pressing enter in search box on the Map page or Hide & Seek page.

* Enhancements:
 - Freemap.SK map sources added.
 - More effective keyword search at http://geocaching.com/seek
 - Postcode lookup from the 'i' menu (UK addresses only).
 - Optional labels for marker circles.
 - Added radius to Plot function to allow plotting circles at specific coordinates, rather than just points (e.g. type `plot r0.2 N51.477 W0` in the search box on the Map page.