[WIP] Replace description NSTextField with NSTextView in NSScrollView

[kristofa]

Unfortunately NSTextView doesn't support placeholder text and the background colour is different from the NSTextFields which is ugly.

[kristofa]

The description field in the popover doesn't has scroll bars which can be confusing when selecting or typing a long description. However you can still see the full description, the text still scrolls even when no visual scroll bars are shown.

This change was an attempt to replace the description NSTextField with a NSTextView embedded in a NSScrollView which would add scroll bars but the implementation has two issues which prevented me from merging:

• There is no placeholder text support for NSTextView. There is some code found on the Internet to mimic placeholder functionality but that adds extra complexity.
• It is surprisingly that the background colour of the NSTextView is different from the NSTextFields and I wasn't able to get them the same in a limited time box. This makes it look ugly.