Now there is a column formatting mechanism.

Now there is a column formatting mechanism.
Modified to customization mechanisms convention.  Doc fix.
(columns): New group for delim-col.
(delimit-columns-before, delimit-columns-after)
(delimit-columns-format, delimit-columns-extra, delimit-columns-start)
(delimit-columns-end): New vars.
(delimit-columns-customize, delimit-columns-format): New funs.
(delimit-columns-region, delimit-columns-rectangle)
(delimit-columns-rectangle-line): Modified to support column
formatting.