This is PAL v0.3.0

Add refraction code and support palOap and palAop. For closer compatibility with SLA for testing purposes the refraction routines internally use clones of slaNutc, slaEqeqx, slaGmst and slaGeoc. Once the code has been verified further the PAL/SOFA routines will be used instead. Switching routines seems to change the results in palTest by about 0.05 arcsec.