Update the .dump command of the command-line shell so that it (1) avoids

Update the .dump command of the command-line shell so that it (1) avoids
putting the semicolon of a DDL statement on the same line as a comment,
(2) avoids long expression, even when dumping a table with many columns, and
(3) avoids unnecessary quoting of the table name.  This fixes tickets
[c04a8b8a4f] and [232637c465].
Shell change only; no changes to the SQLite core.

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