Return to directory of Todd's CASA extensions
Takes 2 strings of format 'YYYY-MM-DD' and returns a new string a specified number
of days before. Can also use 'YYYYMMDD' or 'YYYY/MM/DD'.
Usage:
au.subtractDays(date1, days=1)
Example:
CASA <4>: au.subtractDays('2014-03-01')
Out[4]: '2014-02-28'
CASA <2>: au.subtractDays('2014/01/01')
Out[2]: '2013/12/31'