- Changed name of LatitudeUnits to LongitudeUnits
- Added check to verify that argument of asin is inside (-1,1); slightly
out of range values can result from rounding errors.
- Added setLongitudeDirection method; necessary because longitude increases
eastward (clockwise) in the horizontal coordinate system, ccw in every
other system.
- Parallel spacing was off by a factor of two
- Fixed rotation bug that caused problems with grid orientations other than equatorial and ecliptic
- Allow labeling of longitude in degrees instead of hours