Allow to force editors to wiki editors in object edit mode

Right now the textarea editors displayed in edit mode are based on the properties of the xclass (defining which editor to use) and on user / wiki settings.
This behaviour makes sense, however in some edge cases like for debugging a problem it's handy to actually access the object with the text editor only: right now the solution is always to either change their own settings to force the text editor (which is then applied for every edition) or to change the property of the xclass (which is then applied to everyone for those xobjects).

Instead it would be helpful to have a dedicated URL parameter to allow forcing the editors to fallback on wiki editor.