move extracting planes to camera header

* since it related to view frustum / camera it should be in thie header or separate header called frustum.h
* update LICENSE to add authors of algorithm

src/cam.c

@@ -66,3 +66,9 @@ glmc_lookat(vec3 eye,
             mat4 dest) {
   glm_lookat(eye, center, up, dest);
 }
+
+CGLM_EXPORT
+void
+glmc_extract_planes(mat4 m, vec4 dest[6]) {
+  glm_extract_planes(m, dest);
+}

src/plane.c

@@ -13,9 +13,3 @@ void
 glmc_plane_normalize(vec4 plane) {
   glm_plane_normalize(plane);
 }
-
-CGLM_EXPORT
-void
-glmc_plane_extract(mat4 projView, vec4 dest[6]) {
-  glm_plane_extract(projView, dest);
-}