Add vec_len2d and angle_delta_rad to util.c

src/include/util.h

@@ -26,6 +26,8 @@ bool valid_client(cl_entity_t* ent);
 char* get_name(int ent_idx);
 vec3_t vec3(float x, float y, float z);
 bool vec_is_zero(vec3_t v);
+float vec_len2d(vec3_t v);
+float angle_delta_rad(float a, float b);
 bool world_to_screen(vec3_t vec, vec2_t screen);
 void gl_drawbox(int x, int y, int w, int h, rgb_t c);
 void gl_drawline(int x0, int y0, int x1, int y1, float w, rgb_t col);