Identifier: Enable thread-safety checking.

Enable thread-safety static checker. Fix identified issues:

The code handling sorted iteration over MultiRange was not thread-safe. However, it is not actually used anywhere, so just remove it.

Error handling in ExpandedIdentifier is not thread-safe, but it also mostly useful. Remove, and replace the two places where we might actually report errors with exceptions.

Remove unneeded static, make another static const.

Fix past-the-end indexing error in Range::const_identifier_factory::operator++().

Also fix cppcheck warnings: Better to initialize fields in the initializer list rather then in a ctor body.