TODO

+  2013-08-18: Consolidate with astro (astro is messier and need some clean up,
   in particular the test suite).

+  2013-08-18: Create a Astro.Util.Cyclic module for plusMinusPi, adjustCyclic, et al.
   Or just more them to Astro.Util??

+  2013-08-18: Make specs discoverable. Rename e.g. test/Astro/Util/Tests.hs to 
   test/Astro/UtilSpec.hs and create test/Spec.hs

-  Convert astro tests (see test/Test.lhs) into specs.

-  Fix applyManeuvers (currently NOOP).

-  Why both ephems and trajectories? Can we kill either abstraction?

-  MEOM polation test cases at 1/4, 1/2, 3/4 for a well understood MEOM.

-  Linear interpolation of MEOM longitude isn't consistent with linear
   interpolation of SLR and ecc components as orbital rate varied non-
   linearly with these. Fixing this will be hairy though so I'm
   inclined to leave it as is.

-  Use Lens to access data in the Astro monad.

-  Use Data.Default for the Astro monad.


-  Criterion bench mark.

-  Make At strict in its fields.

-  Use dlists instead of lists.

-  Use vectors instead of lists.


-  Harmonize PosVel and Coord. Retire PosVel?

-  Lenses for data structures (Place, Astro, …)

-  Newtype quantities gratuitiously. SMA a = Length a. Furthermore use symbols (SMA "EH2" a) to ensure consistency in combining symbols.