Add user write permission tests to EESchama and other minor fixes.

* Add general purpose user write permission test function to base
  window class.
* Check user write permissions before saving project, schematic and
  library files.
* Remove displaying file dialog every time the project file is saved.
* Display absolute paths for non-root sheet file in title bar.
* Remove redundant command table entry from schematic editor.
* Remove unused variables to fix GCC 4.6 warnings.
* The usual Doxygen comment and coding style policy fixes.

common/basicframe.cpp

@@ -445,3 +445,35 @@ void EDA_BASE_FRAME::CopyVersionInfoToClipboard( wxCommandEvent&  event )
     wxTheClipboard->SetData( new wxTextDataObject( tmp ) );
     wxTheClipboard->Close();
 }
+
+
+bool EDA_BASE_FRAME::IsWritable( const wxFileName& aFileName )
+{
+    wxString msg;
+
+    wxCHECK_MSG( aFileName.IsOk(), false, wxT( "Invalid file name object.  Bad programmer!" ) );
+
+    if( aFileName.IsDir() && !aFileName.IsDirWritable() )
+    {
+        msg.Printf( _( "You do not have write permissions to folder <%s>." ),
+                    GetChars( aFileName.GetPath() ) );
+    }
+    else if( !aFileName.FileExists() && !aFileName.IsDirWritable() )
+    {
+        msg.Printf( _( "You do not have write permissions to save file <%s> to folder <%s>." ),
+                    GetChars( aFileName.GetFullName() ), GetChars( aFileName.GetPath() ) );
+    }
+    else if( aFileName.FileExists() && !aFileName.IsFileWritable() )
+    {
+        msg.Printf( _( "You do not have write permissions to save file <%s>." ),
+                    GetChars( aFileName.GetFullPath() ) );
+    }
+
+    if( !msg.IsEmpty() )
+    {
+        DisplayError( this, msg );
+        return false;
+    }
+
+    return true;
+}