Add a comment to the sqlite3_index_info structure indicating that the new
field is only available in SQLite 3.8.2 or later.
Fix an error message in the spellfix extension so that it conforms to the 
style of error messages in the core.
Fix for [4065ac8595]: Do not order CROSS or LEFT joins, even if the right-hand-side is a virtual table.
Update test command [explain_i] to handle the opcodes used by virtual tables (VNext, VFilter etc.).
Make sure the count(*) optimization works correctly on WITHOUT ROWID tables.
A better (simpler) fix to the count(*) problem addressed in the previous
check-in.
Import recent bug fixes from trunk.