mmm-client-ui-widget: implement color picker (UiWidgetColorField)

[hohwille]

We need to implement a color picker widget:

• color value (e.g. "#FF00A7") as view label as well as text-box in edit mode
• add a color box beside that shows a little square filled with the color
• in edit mode a click on the color box will open a popup with a detailed color editor form.
• The color editor form may be offered as reusable widget so it can also be used directly and outside the popup.
• The color editor popup should offer RGB as well as HSB mode with the individual 3 values.
• The color editor should offer a rectangle with the entire color scheme to select from.
• The color editor may offer a vertical slice with the current color in a brightness range to select from.
• The color editor may offer a palette with a number of predefined colors to select from. The user may even modify the predefined colors to his personal favor and store them in his client (in web via cookie).
• We will create a datatype Color that is used as value to get and set. It should have getRed(), getGreen(), getBlue(), getHue(), getSaturation(), getBrightness(), etc.
• We will NOT support CYM(K) or color profiles.
• So far we will not support alpha values.