Get ready for release 2.0.0.rc1

Author: rocky

mathics/version.py

@@ -1,8 +1,7 @@
-#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
 
 # This file is suitable for sourcing inside POSIX shell as
 # well as importing into Python. That's why there is no
 # space around "=" below.
-__version__="2.0.0.dev0"  # noqa
+__version__="2.0.0.rc1"  # noqa