Fixed compilation of font_tool.
Do not use kart position if there is no kart
Do not allow specvalue to be below 0.

Just in case it shouldnt be possible anyway.
Tweak fade-in/fade-out times in cutscenes and remove hardcoded values
Merge branch 'master' of https://github.com/supertuxkart/stk-code
Fix negative value inside tonemap

It should be checked before but since it's not always reproducible.
kart selection screen : don't reload RTT scene if the selected kart hasn't changed
Merge branch 'master' of github.com:supertuxkart/stk-code
Merge branch 'master' of https://github.com/supertuxkart/stk-code into kartsound
correct name of file