Add config key SR_CONF_RANGE.

include/libsigrok/libsigrok.h

@@ -1015,6 +1015,9 @@ enum sr_configkey {
 	/** Logic threshold: custom numerical value. */
 	SR_CONF_LOGIC_THRESHOLD_CUSTOM,
 
+	/** The measurement range of a DMM or the output range of a power supply. */
+	SR_CONF_RANGE,
+
 	/* Update sr_key_info_config[] (hwdriver.c) upon changes! */
 
 	/*--- Special stuff -------------------------------------------------*/

src/hwdriver.c

@@ -195,6 +195,8 @@ static struct sr_key_info sr_key_info_config[] = {
 		"Logic threshold (predefined)", NULL},
 	{SR_CONF_LOGIC_THRESHOLD_CUSTOM, SR_T_FLOAT, "logic_threshold_custom",
 		"Logic threshold (custom)", NULL},
+	{SR_CONF_RANGE, SR_T_STRING, "range",
+		"Range", NULL},
 
 	/* Special stuff */
 	{SR_CONF_SESSIONFILE, SR_T_STRING, "sessionfile",