Merge changes made in Gnus trunk.

Merge changes made in Gnus trunk.

shr.el (shr-tag-hr): Use shr-hr-line to specify which character to use to display hr lines.
shr.el (shr-max-columns): Do not change state to nil if we just inserting spaces.
sieve-manage.el (sieve-manage-open): Allow port names as well as port numbers.
shr.el (shr-current-column, shr-find-fill-point): New functions; start thinking about breaking CJVK text.
nnimap.el (nnimap-transform-split-mail): Not all articles have bodies.  Protect against this.
shr.el (shr-insert): Fix up the white space only regexp.
nnimap.el (nnimap-request-rename-group): Select group read-only before renaming it.