Add conversion accuracy and epoch switching tests

README.md

@@ -67,6 +67,8 @@ print(pt.sol)     # 668
 print(pt.hour)    # 14
 print(pt.minute)  # 22
 print(pt.second)  # 7
+print(pt.time)    # "14:22:07"
+print(pt.date)    # "Year 415, Sol 668"
 
 # Mars time since first contact (Viking 1, 1976)
 pt = PlanetaryTime.from_earth(now, Body.MARS, EpochType.CONTACT)