Each effect is able to declare itself as currently being active,
that is transforming windows or painting or screen or doing anything
during the current rendered frame.
This change eliminates the hottest path inside KWin identified by
callgrind.
REVIEW: 102449
First a signal is emitted when the user starts a move/resize operation.
During the move/resize operation each geometry change emits an update signal.
Last but not least a finish signal is emitted.
This eliminates the specific method for geometry updates in drawbound resize
mode.
