Aui project spinner

Hey @blzaugg, I've been trying to embed the UI for this module but it's still not working, so I just spend some last hours today clean the code, add descriptions to the attributes and methods. 

The spinner will be able to perform:

-   Increase/decrease integer and decimal numbers
-   Spin steps can be decimal numbers, step value will change instantly after interaction
-   Type in any number and it will continue to spin based on that value
-   Hold mouse down to spin automatically, the speed of the increment keeps going faster and faster
-   Hold up/down arrow keys in text field to spin automatically
-   Focus will always be on the text field 
-   Input will be parse to `Number`, otherwise value will be reset to 0

There are 2 examples for the spinner located in `demo/spinner`. Thanks