#6 multiple outside temperature sensors - use the one with the lowest reading

Currently when multiple outside temp sensors are used, their readings are published in different ways. In addition to the average, also the median is calculated and published. However this is only useful if more than 2 sensors are used.

It can be configured that the "actual" published outside temperature/humidity reading is taken from calculated "median" or "average", but not "minimum", which would be best when 2 sensors are used and 1 of them is in the direct sun for some time of the day.

Note: this is already published on a separate topic /temp_min

implemented with 74f9ac9d7b - still needs testing.