Move more methods from WorkArea to Clipboard in qt3 and gtk

Move more methods from WorkArea to Clipboard in qt3 and gtk
	* src/frontends/gtk/GWorkArea.[Ch]
	(getClipboard): Move to GuiClipboard.[Ch]
	(putClipboard): ditto

	* src/frontends/gtk/Makefile.am: add GuiClipboard.C

	* src/frontends/gtk/GuiClipboard.C: new file

	* src/frontends/gtk/GuiClipboard.h
	(get, put): only declare

	* src/frontends/qt3/Makefile.am: add GuiClipboard.C

	* src/frontends/qt3/QWorkArea.[Ch]
	(getClipboard): Move to GuiClipboard.[Ch]
	(putClipboard): ditto

	* src/frontends/qt3/GuiClipboard.C: new file

	* src/frontends/qt3/GuiClipboard.h
	(get, put): only declare

	* src/frontends/qt4/GuiClipboard.C: remove unneeded include
	(GuiClipboard::get): adjust debug output
	(GuiClipboard::put): ditto

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@14378 a592a061-630c-0410-9148-cb99ea01b6c8