Bug#805697: implement readline completion

[積丹尼 Dan Jacobson]

Package: sqlite3
Version: 3.9.2-1
Severity: wishlist
File: /usr/bin/sqlite3

<TAB> should complete .help, or show choices.

$ sqlite3 es0.db
SQLite version 3.9.2 2015-11-02 18:31:45
Enter ".help" for usage hints.
sqlite> .he<TAB>