navigator.geolocation wrapping reimplemented
The original implementation was hard to use and often very inefficient.
The user can choose:
* Do not fake my position: useful for example for navigation, i.e. the
user is OK with sharing the position
* Turn geolocation off
* Provide fake navigation. The computed position is in the original
tile (the user can choose the size of the file) and the 8 adjacent:
+----+----+----+
| | | |
+----+----+----+
| |orig| |
+----+----+----+
| | | |
+----+----+----+
Once a visited URL requests the position (fake navigation), JSR returns
the same position until the page reload.