more variable editor improvements; allow more variable types to be edited * ov.h (octave_value::edit_display): New function. * ov-base.h (octave_base_value::edit_display): New virtual function. * ov-base-mat.h, ov-base-mat.cc, ov-base-scalar.h, ov-base-scalar.cc, ov-cell.h, ov-cell.cc: Overload edit_display function. * variable-editor.cc (variable_editor::variable_editor): Increase default width to 30. * variable-editor-model.h, variable-editor-model.cc (make_label): Now file-scope static function instead of member function. (get_rows_and_columns): New file-scope static function. Use to eliminate duplicated code. (impl::cell::cell (const octave_value&, int, int)): New ctor. (variable_editor_model::resize_columns_signal): New signal. (variable_editor_model::update_data): Emit resize_columns_signal when done. (variable_editor_model::variable_editor_model): Connect resize_columns_signal. Don't nest calls to insertRows and insertColumns. (variable_editor_model::type_is_editable) Allow all numeric types, logical arrays, and cells to be edited. Include dimensions in error message.

--- a/libinterp/octave-value/ov.h	Fri Jan 26 00:11:11 2018 -0500
+++ b/libinterp/octave-value/ov.h	Fri Jan 26 19:39:46 2018 -0500
@@ -1275,6 +1275,11 @@
 
   void short_disp (std::ostream& os) const { rep->short_disp (os); }
 
+  std::string edit_display (octave_idx_type i, octave_idx_type j) const
+  {
+    return rep->edit_display (i, j);
+  }
+
   int type_id (void) const { return rep->type_id (); }
 
   std::string type_name (void) const { return rep->type_name (); }