Remove 'Variable Colour' from Sequence Features popup menu

[Edited; was originally: put Variable Colour at the top of the menu.]
Remove 'Variable Colour...' menu option (was 'Graduated Colour...' up to 2.10.5).
Click in the 'Filter' column to open the Variable Colour / Filters dialog.
Reword the column title and tooltip accordingly.
A click in the colour column should still open the colour picker (if a simple colour) or the variable colour dialog (if a variable colour).
To change Variable to simple colour, open the dialog and pick Simple.