(sql-find-sqli-buffer): New function.

(sql-find-sqli-buffer): New function.
(sql-set-sqli-buffer-generally): New function.
(sql-set-sqli-buffer): Better checking of new-buffer.
(sql-copy-column): Add comma after INTO clause, too.
(sql-imenu-generic-expression): New, used to set
imenu-generic-expression.
(sql-mode): Use ?_ and ?. instead of 95 and 46 when
setting font-lock-defaults' SYNTAX-ALIST.  Set
imenu-generic-expression, imenu-case-fold-search, and
imenu-syntax-alist.
(sql-interactive-mode): Use ?_ and ?. instead of 95
and 46 when setting font-lock-defaults' SYNTAX-ALIST.