UnixTime_to_MPL

DatesTimes.UnixTime_to_MPL(UnixTime)

Converts a UNIX time stamp (seconds since the epoch) to matplotlib date/time.

This an its inverse, MPLtime_to_UnixTime() are based on the linear relation between these dates:

  UnixTime       Date/Time      MPL date
------------   --------------   --------
           0   1970,1,1,0,0,0   719163.0
-62135596800      1,1,1,0,0,0        1.0

The slope of MPL date versus UNIX time is 1/(24*60*60)