Modernize!

 - PerlTidy
 - Changes to dist layout
   - Readonly.PM moved to lib/
   - benchmark.pl moved to eg/
 - Milla
   - Makefile.PL replaced by Module::Build::Tiny
   - Prereqs listed in cpanfile
 - Administrative changes
   - Update author and license information
   - Add new repo and issue tracker
   - Require perl 5.6