Draw function never returns true

[philsson]

If the desired value for any layer is not changed, eventually after enough calls to "draw" the current value should reach the desired value. This never seems to happen.

One place this occurs is when running "Display::test()". The exit condition is to get true from "Display::draw()" at the last animation. Instead the max amount of iterations is reached.

Another example is if we for example plot the WiFi status on the top layer, then the top layer is never properly cleared neither calling Display::clear() with specified "All" layers argument or not (Defaults to clear MID layer).

[philsson]

The clear function should maybe clear the current layers, not only the desired values?