Perl 6 renamed to Raku

The pull request changing the name of Perl 6 to Raku has beenmerged. See thefull text for more information. "This document describes the stepsto be taken to effectuate a rename of 'Perl 6' to 'Raku', as described inissue #81. It does not pretend to be complete in scope or in time. Tochange a name of a project that has been running for 19+ years will taketime, a lot of effort and a lot of cooperation. It will affect people inforeseen and unforeseen ways." (Thanks to Sean Whitton)