Add built files, logs, and backups to .gitignore
Add RepositoryFormat6Sha256
Add RepositoryFormat6Sha256
Add the build directory and manpage to .gitignore
Update the version number

Added .18.16 to the version to indicate that (R)on (P)arker had
changed it.
Merge branch 'topic/sha256'
Add Emacs flymake files to .gitignore