[ColorSelectorPopup] no feedback on close/ danger of mistaking the object referred to

[vincent23]

(was #116)

The current implementation has no animations. When tapping on another object although a popup was already open, there is no way to distinguish if the now shown popup refers to the originally pressed or the newly licked object.

I can imagine the following ways to fix this:

• Make the popup explicitly referring to a specific boardobject by positioning it close to it, with an arrow or so pointing on it
• Add fade-ins and -outs so the user sees that something has changed