update main TODO

src/main.cpp

@@ -2,6 +2,7 @@
 /*
  * TODO:
  * - impulsive orbital maneuvers
+ * - update libTangerine to only use xyzw parameters: GLM_FORCE_XYZW_ONLY
  * - replace instances of glm:: with using directives
  * - compile with '-pedantic' and fix macro warnings
  * - convert between satellite state vectors and orbital elements