ErikZalm/Marlin — pull request #390 by buildrob (2013-02-12 10:24:15+00:00)
Title: Implement automatic extruder fan control based on temperature

This change allows fan outputs to automatically turn on/off when the associated extruder temperature is above/below a threshold temperature. Multiple extruders can be assigned to the same pin in which case the fan will turn on when any selected extruder is above the threshold.