Added option for Toggle button to show/hide the picker area.

I added an option to enable a Toggle button below the Palette area, to show or hide the picker area. This gives the user the option to have a limited number of colors to choose from, but also have the possibility to pick a different color, for advanced users.

I also updated the documentation and the example with the new options available.
I added this to have the ability to initialize the picker with 'toggleLessText = false'. This way the picker will always show toggleText. But you're right, your line looks a lot cleaner. And if you want toggleLessText to be the same as toggleText, you just have to initialize it with the same text.