Fixed frame jumps causing the player to move much faster for a short time

fixes http://arx.vg/185
Increase horizontal movement speed while jumping

Some jumps (particularly in the Dwarven level) were excessively hard in
Arx Libertatis. Somewhere along the way we managed to decrease the jump
distance compared to vanilla Arx Fatalis - this is supposed to fix that.

There are still problems where the jump height is decreases with lower
framerates, all jumps I tested where doable at 15fps and higher.

Fixes: bug #413
Fix ladder climbing speed

DeltaTime was applied twice because of previous movement fixes.
Add documentation to util::cmdline::parse
Tweak the jump distance some more

Maybe the previous increase was a bit too excessive.
Merge branch 'player_movement'
Bump years in copyright headers for changed files