Add dublin and julianday converters

add datetime converters for jdc, dc

Assume UTC for naive datetimes in julianday conversion
first draft of babylonian
add babylonian tests
Add to_jd method
babylon helper functions
begin adding intercalarys
Add intercalary (leap month) patterns
formatting and variable names
Use ephem to calculate proleptic babylonian
Update ruler years
babylon: utils for ephemeris and era calculating
move intercalation() to data

Clean up metonic functions
fix regnal year
get current month
Move debug stuff to test dir for now
progress on rising/setting functions
Move to package format
Add dublin converter to babylon
Add data to setup.py
unit tests for babylon
Add parker-dubberstein data