Index: Number of days(Temperature between two values (-2, 2) and precipitation above 0.1 mm/d)

Similar to index functions: CountJointOccurrencesPrecipitationTemperature CountJointOccurrencesTemperature

which inherits from CountJointOccurrences

Replaces #296 (closed)

Note: check if it's ok to add index definition in SMHI_extra.yml.