The demo tests on Mac OS failed because of very tiny
floating point discrepancies that don't matter.
Changed the output of the "Moon check" so that slight
differences in vector residue no longer fail the unit tests.
Added a C# demo program camera.cs that works the same way
as the C demo program camera.c.
I realized I can speed up the C# demo tests by directly
running the executables after I build them, instead of using 'dotnet'.
Added 'vec' field to Equatorial class. I just realized I no longer need
the function VectorFromEquator(), because the vector is now available
as 'vec'. I will get rid of it in another commit.
