This function calculate the difference in time (minutes) between the waypoint end and start.
check_time(data)A dataframe obtained from the function "spygen_waypoint". It must contain the following columns : "spygen_code", "date", "latitude_start_DD", "longitude_start_DD", "latitude_end_DD", "longitude_end_DD", "project", "time_start", "Time_waypoint_start", "Time_waypoint_end".
A dataframe with a column named "diff_time_waypoints", indicating the difference in time (minutes) between the waypoint end and start.