Make fts1.c not rely on nul-terminated strings. Mostly a matter of

Make fts1.c not rely on nul-terminated strings.  Mostly a matter of
making sure we always pass around ptr/len, but there were a few places
where we actually relied on nul-termination.

An earlier change had additionally changed appropriate
sqlite3_bind_text() calls to sqlite3_bind_blob().  I've found that
this changes what's actually stored in the database, so backed those
changes out.  Also (and this is weird), I found that I could no longer
do straight-forward = queries against %_term.term at a command-line. (CVS 3379)

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