[core] Cleanup some dead code from AbstractDesktopView

code cleanup, remove dead and unused code, and some debug
messages.
[port] Port PlexyDesk to Qt5

http://redmine.plexyplanet.org/issues/271

PlexyDesk Now Compiles with Qt5 and this commits drops support for
Cmake 2.6 and Qt4.

Conflicts:

	CMakeLists.txt
	base/core/abstractdesktopview.cpp
	extensions/desktop/plexy/plexydesktopview.cpp
[build] Make plexydesk compile on Linux with Qt5

Build fixes for Linux

refs #271
[build] Fix linker error on Linux

Fix linker error on Linux (64bit)
[build] Add back OpenGL package

Add the opengl dep which got lost during rebase
[build] Fix compilation errors on Linux