Adds a "Copy source" action to the right click menu of cumbia-qtcontrols widget supporting contextual menus

cumbia-qtcontrols widgets that use CuContextMenu to provide a right click menu will add a Copy source action that copies the source (or target) of the widget into the clipboard. The source (target) is copied as plain text.

To install the plugin, execute

• qmake
• make
• make install

after checking that the line

include(/usr/local/cumbia-libs/include/cumbia-qtcontrols/cumbia-qtcontrols.pri)

in the file cumbia-copy-source-context-menu-actions.pro is correct (in the default case, cumbia-qtcontrols is installed under /usr/local/cumbia-libs)

Have fun.