loxodrome_direct stability near asymptote, enhance CI
CI tests Python 3.7...3.10
Added stability to loxodrome_direct for azimuth = {90,-90,270,-270}
enhanced efficiency of loxodrome_inverse for stability
CI tests Python 3.7...3.10
Added stability to loxodrome_direct for azimuth = {90,-90,270,-270}
enhanced efficiency of loxodrome_inverse for stability