Function notify

notify(json?): void
Show a pop-up notificaiton to the user.
Parameters
- json: {
      caption: string;
      color: string;
      icon: string;
      message: string;
      position: string;
      text-color: string;
      timeout: number;
      type: string;
  } = ...
  - caption: string
    string: Caption below the message (optional)
  - color: string
    string: The background color of the notification (optional)
  - icon: string
    string: The name of an mdi icon (optional)
  - message: string
    string: The body of the message
  - position: string
    string: One of "top-left | top | top-right | left | center | right | bottom-left | bottom | bottom-right" (optional)
  - text-color: string
    string: The color of the text (optional)
  - timeout: number
    number: number of milliseconds to display the notification (optional)
  - type: string
    string: "positive | negative | warning | info | ongoing", auto assigns appropriate color and icon. (optional)
Returns void
Example
```
// put a red warning message at the top of the screen for 3 seconds
{"message": "testing", 
"caption": "a caption", 
"position": "top", 
"type": "warning", 
"timeout": 3000}

// simplest form
{"message": "testing"}
```