Added first script to find unused files in STK.
Renamed XMLWriter to UTFWriter (which is the correcter name).
Added new player manager, and started to replace the saved data
from user_config with player manager.
Fixed linux compilation.
Removed m_all_players from UserConfigParams (though there are stil
bugs in the new code).
Merge branch 'new_login' of github.com:hiker/stk-code into new_login
Started to move current player info from unlock manager into
player_manager.
Shadow: reenable shadows

It's just plain basic shadowmaps, a lot of tweak is still necessary but
it gives a way to see how light values are affected in some places.
(cave in chocolate for instance)
Shadow: Better bias.
Shadow: soften edge a little
Shadow: Fix broken specular with shadows enabled.
Lights: Remove unused export value.
Various compilation fixes, some cosmetic changes.
Shadow: Support for alpha tested meshes.
Removed all references to current user/slot from unlock manager.
Shadow: Grass now cast shadows.
Removed loading and saving of challenge.xml file.
Made sorting of players descending (instead of using > in operator<),
removed kart and unique id from game slot, replaced some forgotten calls to
unlock_manager with calls to PlayerManager.
Fixed running on hd3000 (8192 was too big for my system, not sure
what values should be used best, I used the previous code here).
Merge remote-tracking branch 'upstream/master' into new_login

Conflicts:
	src/challenges/game_slot.cpp
	src/states_screens/kart_selection.cpp
	src/tracks/track.cpp