Add support for favorite level and fix speed change

[mouth4war]

piid 8 (motor1-speed) is not writable as per spec and seems to just report motor speed. It now seems possible to directly change favorite mode motor speed via piid 7 (m1-favorite).

Propose

1. renaming current changeFavorite to changeFavoriteSpeed.
2. adding properties for motor_speed and favorite_level
3. defining new changeFavoriteLevel to directly set favorite_level

Relevant spec:

Service: siid 10: (motor-speed): 10 props, 0 actions
    * Property piid: 1 (m1-strong): (int32, unit: None) (acc: ['read', 'write'], value-list: [], value-range: [300, 2300, 10])
    * Property piid: 2 (m1-high): (int32, unit: None) (acc: ['read', 'write'], value-list: [], value-range: [300, 2300, 10])
    * Property piid: 3 (m1-med): (int32, unit: None) (acc: ['read', 'write'], value-list: [], value-range: [300, 2300, 10])
    * Property piid: 4 (m1-med-l): (int32, unit: None) (acc: ['read', 'write'], value-list: [], value-range: [300, 2300, 10])
    * Property piid: 5 (m1-low): (int32, unit: None) (acc: ['read', 'write'], value-list: [], value-range: [300, 2300, 10])
    * Property piid: 6 (m1-silent): (int32, unit: None) (acc: ['read', 'write'], value-list: [], value-range: [300, 2300, 10])
    * Property piid: 7 (m1-favorite): (int32, unit: None) (acc: ['read', 'write'], value-list: [], value-range: [300, 2300, 10])
    * Property piid: 8 (motor1-speed): (int32, unit: None) (acc: ['read'], value-list: [], value-range: [0, 3000, 1])
    * Property piid: 9 (motor1-set-speed): (int32, unit: None) (acc: ['read', 'write'], value-list: [], value-range: [0, 3000, 1])
    * Property piid: 10 (favorite fan level): (int32, unit: None) (acc: ['read', 'write'], value-list: [], value-range: [0, 14, 1])

[mouth4war]

rytilahti/python-miio#585 (comment)

[mouth4war]

So it looks like setting motor speed via piid 9 doesn't work. Favorite mode rpm can be set via piid 7.

[mouth4war]

@kingkong123 ready for review/tests

[kingkong123]

@mouth4war sorry for late reply, a bit busy these days.
Thanks for the PR, looks great

[github9984]

How do I test this? Do I just copy and overwrite miio folder?

[kingkong123]

I think you better update the dependency in package.json to this repo and run npm install to install the package

"dependencies": {
    "miio": "github:kingkong123/miio"
  }

[github9984]

fan-speed.js is loading with errors.
Fs1 = -1;