Fix the ".echo on" dot-command of the shell so that it echos comments in
addition to SQL statements and dot-commands.  Add the --explain option
to speedtest1 so that the output can be piped into the command-line shell
to show nicely-formated VDBE code for the entire test.
Fix harmless compiler warnings in FTS4.  This involved corrupting
Martin Porter's beautifully written and elegant stemmer code, making it
a little less beautiful and a little less elegant.  Today is a sad
day.  But the warnings from GCC grow increasingly verbose and irksome
with each new release and so something had to be done.
Avoid compiler warnings by only enabling sqlite3ErrName() when
SQLITE_TEST is defined.
Fix speedtest1.c so that in --explain mode it only outputs non-explain text
for DDL statements.