Add EVF event file parser

Add support for EVF events file reader:

#EVENTS GENERATED BY THE GEOPIPELINE ON Fri Dec 17 00:07:17 2021
#Retrieved from juice_flybys_science_phase_crema_5_0 using the following query:
#SELECT * FROM  juice_flybys_science_phase_crema_5_0 WHERE evt_type IN ("peri") AND target IN ("europa")
22-JAN-2031_18:54:03    CA_EUROPA      (COUNT =  1)
26-JAN-2031_08:08:00    CA_EUROPA      (COUNT =  2)
29-JAN-2031_21:21:56    CA_EUROPA      (COUNT =  3)
...

Added

New EvfEventFile was added:

from moon_coverage.events import EvfEventsFile

EvfEventsFile('CA_EUROPA.EVF')

returns:

event	#	t_start	t_stop
CA_EUROPA	3	2031-01-22	2031-01-29

EvfEventFile is based on AbstractEventsFile and EventsDict objects.

It supports the same search/filtering methods as EventsDict and EventsList.

Changes

• EventFile was renamed CsvEventFile.

Deprecated

• EventFile is depreciated. Use CsvEventFile instead.

Other fixes

• Fix Poetry version in readethedocs.yml config
• CHANGELOG link in docs/ folder
• Fix spelling typos