DOCS-1504: chardisplay

interface CharDisplay {
    Promise<void> Show(in unsigned long row, in unsigned long col, in DOMString text)
    Promise<void> Clear()
    Promise<void> SetPos(in unsigned long row, in unsigned long col)
    Promise<void> SetCursor(in unsigned long cursor) // 0=off, 1=blink, 2=underline, 3=both
    Promise<void> SetContrast(in unsigned long contrast) // 0-100
    Promise<int> GetContrast()
    Promise<void> SetBrightness(in unsigned long brightness) // 0-100
    Promise<int> GetBrightness()
}

var chardisplayClass = require("@brightsign/chardisplay");
var chardisplay = new chardisplayClass();

Promise<void> Clear()