Commit 344d9765936 resulted in the start of Subsurface with a map of the whole world. The user has to zoom in (assuming the case that the first selected dive has a position), in evenry session. This is solved by setting the zoomlevel at startup at the default value. Ok, this results in a map of central London, UK, when starting Subsurface with a dive without location, but is this as good as any map. Signed-off-by: Jan Mulder <jlmulder@xs4all.nl>