Since some time PlasmaCore had the very useful ColorScope class,
which can semi-automatically make children take colors of the
View, Button or Complementary color groups.
Unfortunately it didn't support dynamic reparenting, giving
wrong colors in some cases (see black on black battery on the phone)
even tough is a bit complicated, now by cascading signals down the
children tree, support on the fly apply of the new context upon
reparenting.
also add a manual test case showing text, rectangles and icons
dynamically changing color as they get moved from one scope
to the other
REVIEW:126654
Change-Id: I3d746b73eac55a359c4706fb719b4d5018677fb5
