Foce rename

git is not seeing the rename from symbolEditor.css to SymbolEditor.css.  Pluralizing to get git to pick up the change.
rename SymbolEditors.css --> SymbolEditor.css

previous commit forced git to pick up the capitalization issue.  This commit renames back to original, singular, name.
Edit graphic symbols

switched all symbol editors to use AccordionContainers due to problems using TabContainers.  Used in Dialog, could not get tabs to display.
_SymEditorMixin unit tests

basic unit tests for _SymEditorMixin - all passing