bump version to 6.4

bump version to 6.3

Prepare 6.2 release.

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