Autoload dynamic block definitions
* lisp/org-colview.el: Autoload call to org-dynamic-block-define.
The dynamic block dispatcher added in 34b71a0ca (Add a dispatcher
command for inserting dynamic blocks, 2018-12-23) offers an entry for
"clocktable" and "columnview" only after the corresponding library is
loaded. However, before that commit, the autoloaded org-clock-report
and org-columns-insert-dblock commands were accessible via plain key
bindings. Restore the ability to access these commands before the
associated library is loaded.
Reported-by: Axel Kielhorn <firstname.lastname@example.org>