Make ToString work properly for Expressions classes and automaton components
If you hover over a C# expression in the graphical debugger, it uses object.ToString() to give an informative summary of the result of evaluating that expression. However, for C# objects that represent Modest expressions, all ToString does is return the root operator symbol. For example, the object tree representing the expression "(x + 7) * a[i]" is summarized to the very uninformative string "*". We already have formatting for Expressions, so it should not be that big of a deal to make ToString return proper summaries.