Shadow: tweak bias to remove acnee
Use  glPolygonOffset to remove shadow acne

It's a 2002 trick from M. Kilgard
NormalMap should cast shadows too
Temporary comment out exposure/lwhite settings
Reenable ability to change exposure/lwhite.
Honor the per-track flag to disable god rays
Tonemap: Use J. Hable filmic operator

It gives better result on stk enterprise, slightly saturating blacks.
Auria provided tonemap coefficients
Very slight tweak
Missing "track->hasShadows" check
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
Fix bullet assertion failure