Update UI player animation handling to match CGame

Fix "Error parsing animation file" messages in UI. Caused by fixing the
handling of missing tokens in animation.cfg parser in a past commit.
Fix new Team Arena torso animation frame numbers in UI.
Add support for fixedtorso and fixedlegs keywords.
Add support for reversed animations (negative numframes).

code/q3_ui/ui_local.h

@@ -486,6 +486,9 @@ typedef struct {
 
 	animation_t		animations[MAX_ANIMATIONS];
 
+	qboolean		fixedlegs;		// true if legs yaw is always the same as torso yaw
+	qboolean		fixedtorso;		// true if torso never changes yaw
+
 	qhandle_t		weaponModel;
 	qhandle_t		barrelModel;
 	qhandle_t		flashModel;