Fix double class name

Mostly cosmetic change, although there are compilers that choke on this.

The C++ standard specifies that classes contain themselves as members,
probably so they shadow any other definition of the same name for their own
member functions, but there is really no reason why the class name should
be duplicated here.

pcbnew/files.cpp

@@ -378,7 +378,7 @@ IO_MGR::PCB_FILE_T plugin_type( const wxString& aFileName, int aCtl )
     {
         pluginType = IO_MGR::LEGACY;
     }
-    else if( fn.GetExt() == IO_MGR::GetFileExtension( IO_MGR::IO_MGR::PCAD ) )
+    else if( fn.GetExt() == IO_MGR::GetFileExtension( IO_MGR::PCAD ) )
     {
         pluginType = IO_MGR::PCAD;
     }