20210928a

• Implement a >rename command and refactor overrides of LibraryItem.Rename and related code.
• Support generating a cross-reference that excludes line numbers.
• When changing an fn_name string literal, also change its variable name so that it follows the Scope_Function naming convention.
• Don't log Indentation on a C-style comment.
• Fix bug: FunctionUnused was no longer logged on a class function with a separate definition.
• Fix bug: if a function declaration had an anonymous argument, DefinitionRenamesArgument was also logged on the definition's argument.
• Fix bug: DataUnused was no longer logged on a static class member with a separate definition.
• Fix bug: a data definition not initialized using operator= did not have its declaration as its referent.
• Fix bug: in Editor.Replace, only update the positions where characters are erased or inserted, not modified, to prevent a C++ item from being marked as erased when it is only being renamed.
• Fix bug: when Editor changes a C++ item, use Replace instead of Erase and Insert (Erase causes an item within its span to be marked as erased, which prevents subsequent edits).