code-style consistency

bump version to 6.0

enabled release flags

increased version

removing Sylvain's patch because it breaks more than it fixes unfortu…

…nately, re-issuing a bugfix release 5.8.1

removed DEBUG code and added 2010 to the copyright list

applied Ryan Zheng's patch and re-releasing 5.7.2

fixed the layout symbol bug reported by Nibble (but using a different…

… approach as he suggested)

- optimised drawbar() and arrange() handling for multiple monitors, arrange only arranges the relevant monitors when applicable, same with drawbar
- need to release 5.7.1

switching to release flags

applied nsz patch