Prevent long delays clearing console

This change avoids very long delays as the escape sequences are reprocessed when you ask to clear a console containing a large amount (mb) of output. To replicate download https://github.com/johnno1962/Xtrace, enable coloring on line 150 of XRAppDelegate.m run the application and then clear the console. There is often a very long delay this fix replaces the escape sequence avoiding their being processed twice.