Changes from v1.2 to v1.3

• Convert to pure python.

Changes from v1.1 to v1.2

New Features

• Added CelestialCoord.greatCirclePoint method

• Added Angle.deg property

• Enabled <, >, <=, >= comparisons between Angles

Changes from v1.0 to v1.1

New Features

• Added xyz_to_radec and radec_to_xyz

• Added AngleUnit.valid_names class attribute

Bug Fixes

• Fixed error in postel projection with array input.

• Close the files that are opened when reading headers for ffi.