This version of the API shipped with Indigo 6 beta 8 - check the API Version Chart to see what version of the API is available in which Indigo versions.
indigo.server.apiVersion attribute which returns the Indigo Server's current plugin API version as a string (ex: “1.7”). The plugin can then use this value to add conditionals around calling newer APIs while maintaining backwards compatibility with older versions of Indigo Server.dehumidifierIsOn and humidifierIsOn attributes to the thermostat device class. These attributes are set to True for some thermostats (2441TH, 2441ZTH) when their humidity setpoints are crossed to turn ON/OFF dehumidifiers and humidifiers.updateTimeStampOnServer() method to device instances to increment last changed timestamp on a device.