feat!: multi-click selection by word and line and a color picker

[clearloop]

• editor: dragging after a double or triple click extends by word or line; a triple click takes the logical line; ctrl-k kills to the line end; no caret over a selection
• ui: TextField gets double and triple click selection with the same drag
• terminal: view::selection_type maps a click count to its selection granularity
• editor: anchors live in the shown document's coordinates, so find hits and comments paint in source mode (Bug: Keep article search results highlighted regardless of focus cydonia#80)
• markdown (breaking): selectable Pointer::Down carries click granularity
• ui: cross-platform color picker