faster version of XYZ_to_lbd, see #162
introduce decorators to handle degree in/output and scalar in/output
remove old XYZ_to_lbd
doc tweak
speed up radec_to_lb (#162) and fix degree decorator
speed up lb_to_radec (#162) and fix degree decorator
speed up lbd_to_XYZ (#162)
speed up vrpmllpmbb_to_vxvyvz (#162)
speed up vxvyvz_to_vrpmllpmbb (#162)
comments about decorators
speed up pmrapmdec_to_pmllpmbb (#162)
speed up pmllpmbb_to_pmrapmdec, fixes #162