Unit test for Timeserie class routines.

• module_timeserie.datetime2data
• module_timeserie.concatenate
• module_timeserie.sort

Reference timeserie:

• Time axis: datetime serie for 2018-jan-1T00:00:00 to 2018-jan-1T23:00:00, 1h interval.
  
• Data: 2d-tuple, (integer,float).