score gradient process ideas and suggestions

[ ] point management should be consistent with other processes, i.e. at least from a menu on right-click (and potentially in better ways, see #481)
[ ] IMO the first point should be based on the color value of the first state, and the last point on the one of the end state
[ ] when adding a point it should query the current value of the associated address if there is one
[ ] when choosing a color from i-score's color picker it should be output (ideally it would be great if the color be output continuously when moving the "target" of the color picker
[ ] it would also be very very cool that a gradient be created when 'interpolating states' or creating a sequence (see #480)
[ ] add a (0. to 1.) curve, such as in interpolations between each point pair, in order to change the 'transition' shape between two color values
[ ] not sure about this, but maybe there could be more advanced ways to interpolate between colors (I'm thinking about duration's "color palette" for interpolation) - not for next month, I guess, but probably worth discussing

Jun 06 '17 18:06 bltzr

[ ] also, the position should be clipped at the beginning at the process (or the point moved to the left is lost)

Jun 06 '17 19:06 bltzr

cherry-picked from #468

Jun 21 '18 08:06 bltzr