Added 'strict_parsing' option to all parsing functions. This causes a

Added 'strict_parsing' option to all parsing functions.  This causes a
ValueError exception when the query string contains fields that don't
contain exactly one '=' sign.  (By default, such fields are simply
ignored.)  Added this to the doc string describing parse() and
parse_qs().

Also changed the default for keep_blank_values from None to 0 (the
preferred way to spell 'FALSE').