Replaced COPYING with LGPL2-only license
Replaced COPYING with LGPL2-only license

There is not a single file in gtk-sharp that has a LGPL2.1+ header but
LGPL2-only instead.

sillsdev/gtk-sharp,antoniusriha/gtk-sharp,orion75/gtk-sharp,openmedicus/gtk-sharp,openmedicus/gtk-sharp,orion75/gtk-sharp,Gankov/gtk-sharp,orion75/gtk-sharp,antoniusriha/gtk-sharp,antoniusriha/gtk-sharp,sillsdev/gtk-sharp,Gankov/gtk-sharp,antoniusriha/gtk-sharp,openmedicus/gtk-sharp,orion75/gtk-sharp,akrisiun/gtk-sharp,akrisiun/gtk-sharp,akrisiun/gtk-sharp,antoniusriha/gtk-sharp,Gankov/gtk-sharp,openmedicus/gtk-sharp,sillsdev/gtk-sharp,openmedicus/gtk-sharp,orion75/gtk-sharp,sillsdev/gtk-sharp,akrisiun/gtk-sharp,sillsdev/gtk-sharp,openmedicus/gtk-sharp,Gankov/gtk-sharp,openmedicus/gtk-sharp,Gankov/gtk-sharp,akrisiun/gtk-sharp,Gankov/gtk-sharp