Remove an unneeded namespace qualifier.

This makes testing with SDL 2.0 easier

git-svn-id: http://svn.gna.org/svn/wesnoth/trunk@56399 75b3775d-3801-0410-9e12-e2e43121521d
Add SDL 2.0 compatibility.

Rewrites the joystick code so it works with both SDL 1.2 and SDL 2.0.

git-svn-id: http://svn.gna.org/svn/wesnoth/trunk@56400 75b3775d-3801-0410-9e12-e2e43121521d