[Client] Remove quest target markers

The quest target markers are not removed properly from the mini map in
case a new quest is selected. This problem is now fixed.
[Client] Fix issue #9179: New quest markers appear too high

http://illarion.org/mantis/view.php?id=9170
Questmarkers were displayed too high above a tile.
To correct this issue one should not use "appliedOffset".
[Client] Adding targetmarker by mouseover

http://illarion.org/mantis/view.php?id=8786
Added a very rudimentary system for a targetingsystem.
[Client] Fix copyright note
[Client] Remove/add skills properly from/to skill window.

http://illarion.org/mantis/view.php?id=9175
Remove skills if their value is 0 and display them when aquired by redisplaying the window if it is visible.
Merge branch 'quintar' into develop
[Client] Show all available quest target markers

http://illarion.org/mantis/view.php?id=9169
Show all quest markers on the avatar and the mini map.
Paint the current Quest(giver) in red.
[Client] Remove Quest-markers when quest is finished

http://illarion.org/mantis/view.php?id=9169
Show all quest markers on the avatar and the mini map.
Paint the current Quest(giver) in red.
Remove markers when finished.