EESchema dead code removal and other minor changes.

* Move code from function ClearProjectDrawList() into SCH_SCREEN object
  Clear() method.
* Delete eeschema/delsheet.cpp as none of the code in it is ever called.
* Move global spice and net list command line variables into SCH_EDIT_FRAME
  object as priviate members and provide access methods.
* Remove unnecessary header includes from eeschema/sheet.cpp.
* Minor coding policy fixes.

eeschema/sheet.cpp

@@ -12,21 +12,16 @@
 #include "fctsys.h"
 #include "gr_basic.h"
 #include "common.h"
-#include "macros.h"
 #include "class_drawpanel.h"
 #include "confirm.h"
-#include "gestfich.h"
 #include "wxEeschemaStruct.h"
 #include "class_sch_screen.h"
 
 #include "general.h"
-#include "protos.h"
 #include "sch_sheet.h"
 
 #include "dialogs/dialog_sch_sheet_props.h"
 
-#include <boost/foreach.hpp>
-
 
 bool SCH_EDIT_FRAME::EditSheet( SCH_SHEET* aSheet, wxDC* aDC )
 {