Basic subtitution of SOFA by ERFA
Remove further references to SOFA, now in docs
Updated changelog
Updated the last iau prefixed function
ERFA change message moved, minor grammar tweak
Using the full permission text
In 0.2 we are using SOFA, not ERFA
Merge branch 'master' into erfa

Conflicts:
	CHANGES.rst
Longer explanation of the SOFA -> ERFA change
Merge pull request #1293 from sergiopasra/erfa

Change SOFA to ERFA