elm_colorselector: selected item is updated when color is changed.

elm_colorselector: selected item is updated when color is changed.

Summary:
 - Previously, mode change, color change updated
   sd->selected, but did not send signals to edje of the item.
 - Also, mode change in colorselector set sd->selected to
   the first item even when palette is visible in previous mode.
 - Now, when mode is changed, sd->selected is set NULL and send
   unselected signal if palette is invisible, and keep sd->selected
   if palette is visible.
 - sd->selected is set NULL when color is changed in picker and
   color bars because previous selected item is not current color of
   colorselector

Test Plan:
1.
    1) launch elementary_test colorselector.
    2)Select any item and check the item is selected when palette is visible.
    3) Change mode to Palette, Both, All, and check selected item is not changed.
    (Previously, selected item is changed to the first item of the palette, but previous item was seen as selected.)

2.
    1) launch elementary_test colorselector.
    2) Select any item and check the item is selected when palette is visible.
    3) Change mode to Components, Picker.
    4) Change mode to Palette, and check none of items is selected.
    (Previously, selected item is changed to the first item of the palette, but previous item was seen as selected.)

3.
    1) launch elementary_test colorselector.
    2) Select any item and check the item is selected when palette is visible.
    3) Change mode to All.
    4) Click arrows in Picker and color bars.
    5) Observe selected item is not unselected when color is not changed, and selected item is unselected when color is changed.
4.
    1) launch elementary_test colorselector.
    2) Select any item and check the item is selected when palette is visible.
    3) Press direction key and check selected item is changed.
    (Previously, selected item's edje is not updated.)

Reviewers: woohyun, Hermet, jpeg, cedric

Subscribers: cedric, jpeg

Differential Revision: https://phab.enlightenment.org/D4156

Signed-off-by: Cedric BAIL <cedric@osg.samsung.com>