#44 Set color temperature in Mirek for lights and rooms (#48)

It is now possible to set the color temperature in Mirek for lights and
rooms.

### Examples: 

Set color temperature (in Mirek) of a single room:
```
openhue set light Studio --on --temperature 250
```
Set color temperature (in Mirek) of a single light:
```
openhue set light Desktop --on -t 490
```
Closes #44

cmd/set/common.go

@@ -12,13 +12,14 @@ import (
 //
 
 type CmdSetLightFlags struct {
-	On         bool
-	Off        bool
-	Brightness float32
-	Rgb        string
-	X          float32
-	Y          float32
-	ColorName  string
+	On          bool
+	Off         bool
+	Brightness  float32
+	Rgb         string
+	X           float32
+	Y           float32
+	ColorName   string
+	Temperature int
 }
 
 func (flags *CmdSetLightFlags) initCmd(cmd *cobra.Command) {
@@ -48,8 +49,11 @@ func (flags *CmdSetLightFlags) initCmd(cmd *cobra.Command) {
 		return color.GetSupportColorList(), cobra.ShellCompDirectiveDefault
 	})
 
+	// temperature
+	cmd.Flags().IntVarP(&flags.Temperature, "temperature", "t", -1, "Color temperature in Mirek [min=153, max=500]")
+
 	// exclusions
-	cmd.MarkFlagsMutuallyExclusive("color", "rgb", "cie-x")
+	cmd.MarkFlagsMutuallyExclusive("color", "rgb", "cie-x", "temperature")
 }
 
 // toSetLightOptions makes sure provided values for LightOptions are valid
@@ -72,6 +76,13 @@ func (flags *CmdSetLightFlags) toSetLightOptions() (*openhue.SetLightOptions, er
 		o.Brightness = flags.Brightness
 	}
 
+	// validate the temperature flag
+	if flags.Temperature > 500 || (flags.Temperature != -1 && flags.Temperature < 153) {
+		return nil, fmt.Errorf("--temperature flag must be greater than 153 and lower than 500, current value is %d", flags.Temperature)
+	} else {
+		o.Temperature = flags.Temperature
+	}
+
 	// color in RGB
 	if flags.Rgb != "" {
 		rgb, err := color.NewRGBFomHex(flags.Rgb)

cmd/set/set_light.go

@@ -36,6 +36,9 @@ openhue set light 15f51223-1e83-4e48-9158-0c20dbd5734e --on -x 0.675 -y 0.322
 
 # Set color (by name) of a single light
 openhue set light 15f51223-1e83-4e48-9158-0c20dbd5734e --on --color powder_blue
+
+# Set color temperature (in Mirek) of a single light
+openhue set light MyLight --on -t 250
 `
 )
 

cmd/set/set_room.go

@@ -35,6 +35,9 @@ openhue set room 15f51223-1e83-4e48-9158-0c20dbd5734e --on -x 0.675 -y 0.322
 
 # Set color (by name) of a single room
 openhue set room 15f51223-1e83-4e48-9158-0c20dbd5734e --on --color powder_blue
+
+# Set color temperature (in Mirek) of a single room
+openhue set light Studio --on -t 250
 `
 )
 

openhue/home_model.go

@@ -70,16 +70,18 @@ type Device struct {
 //
 
 type SetLightOptions struct {
-	Status     LightStatus
-	Brightness float32
-	Color      color.XY
+	Status      LightStatus
+	Brightness  float32
+	Color       color.XY
+	Temperature int
 }
 
 func NewSetLightOptions() *SetLightOptions {
 	return &SetLightOptions{
-		Status:     LightStatusUndefined,
-		Brightness: -1,
-		Color:      color.UndefinedColor,
+		Status:      LightStatusUndefined,
+		Brightness:  -1,
+		Color:       color.UndefinedColor,
+		Temperature: -1,
 	}
 }
 
@@ -135,6 +137,12 @@ func (light *Light) Set(o *SetLightOptions) {
 		}
 	}
 
+	if o.Temperature >= 153 && o.Temperature <= 500 {
+		request.ColorTemperature = &gen.ColorTemperature{
+			Mirek: &o.Temperature,
+		}
+	}
+
 	if o.Color != color.UndefinedColor {
 		request.Color = &gen.Color{
 			Xy: &gen.GamutPosition{
@@ -173,6 +181,12 @@ func (groupedLight *GroupedLight) Set(o *SetLightOptions) {
 		}
 	}
 
+	if o.Temperature >= 153 && o.Temperature <= 500 {
+		request.ColorTemperature = &gen.ColorTemperature{
+			Mirek: &o.Temperature,
+		}
+	}
+
 	if o.Color != color.UndefinedColor {
 		request.Color = &gen.Color{
 			Xy: &gen.GamutPosition{