Fix back button in login screen and fix 'move on uninitialised value in MusicInformation'
Fix back button in the register screen and login as guest
Fix back button size in guest login screen
Bugfix : use ambient light from the sun when SH maps are not used
Tigher fit of light extent
Tweak light attenuation.

Doesnt really change the look of the light but reduce their extent.
Improve flying mode
Improve flying mode, part 2
Merge pull request #1303 from leyyin/master

Fix some bugs in the online screens
Merge branch 'master' of https://github.com/supertuxkart/stk-code into grand_prix