Toward alpha2

Progress is coming along.
After fixing the known bugs, i did quite some small improvements all around, a bit difficult to detail. Let'sjust say from cosmetics to usage improvements. I am trying to follow up on all your inputs.

I have also fixed a bug which prevented proper caslibration from map files, now it works again.

Also, i am reimplementing tracks statistics and graphics, it's coming along pretty nice.
Things still to do before alpha2:
- Improve online maps (add more sources & make interface more usable)
- add text summary statistics (at the moment, only graphics)

Then if i have time i also want to fully rewrite the map import code to use internal Qt libs and thus dropping the limit of JPG/PNG only maps!