0.30-2 (for CRUSH 2.50-2)

This updated 0.30 release contains several bug fixes.

• Fix parsing negative angles in AngleFormat class
• Fix FITS header writing/parsing in Grid2D
• Fix FITS header parsing and error handling in CoordinateEpoch
• Correct FITS WCSAXES in AbstractMap2D1
• Default to J2000 epoch for PrecessingCoordinates