Eeschema: Clear drawing state when loading project

Prevents stray flags from entering schematic editing process

Fixes: lp:1738894
* https://bugs.launchpad.net/kicad/+bug/1738894

eeschema/files-io.cpp

@@ -377,6 +377,7 @@ bool SCH_EDIT_FRAME::OpenProjectFiles( const std::vector<wxString>& aFileSet, in
     Zoom_Automatique( false );
     SetSheetNumberAndCount();
     m_canvas->Refresh( true );
+    GetScreen()->ClearDrawingState();
 
     return true;
 }