Suppress continuation prompts in SQL interactive mode

Suppress continuation prompts in SQL interactive mode

        * progmodes/sql.el: Version 2.5
        (sql-product-alist): Add :prompt-cont-regexp property for several
        database products.
        (sql-prompt-cont-regexp): New variable.
        (sql-output-newline-count, sql-output-by-send): New
        variables. Record number of newlines in input text.
        (sql-send-string): Handle multiple filters and count newlines.
        (sql-send-magic-terminator): Count terminator newline.
        (sql-interactive-remove-continuation-prompt): Filters output to
        remove continuation prompts; one for each newline.
        (sql-interactive-mode): Set up new variables, prompt regexp and
        output filter.
        (sql-mode-sqlite-font-lock-keywords): Correct some keywords.
        (sql-make-alternate-buffer-name): Correct buffer name in edge
        cases.