core: make WorldEntity rotation a quaternion.

src/worldentity.cpp

@@ -26,7 +26,7 @@ namespace lol
 WorldEntity::WorldEntity()
 {
     m_position = vec3(0);
-    m_rotation = vec3(0);
+    m_rotation = quat(1);
     m_velocity = vec3(0);
     m_bbox[0] = m_bbox[1] = vec3(0);
 

src/worldentity.h

@@ -25,8 +25,8 @@ class WorldEntity : public Entity
 {
 public:
     vec3 m_position;
-    vec3 m_rotation;
     vec3 m_velocity;
+    quat m_rotation;
     vec3 m_bbox[2];
 
     ivec2 m_mousepos;