https://bugs.launchpad.net/tarantool/+bug/1200228
Remove the regression I introduced when trying to be to smart when
comparing integer numbers.

Numeric comparison is not memcmp compatible on x86, and I don't
know what I was smoking when I wrote a test which proved it wrong.

Apparently until I stop bullshitting ppl in the tagline I won't get
my hands on to finishing this feature (been 6 months since it was on a
branch).

Remove Debian Squeeze support.

Save tuple field offsets for indexed fields in the tuple.
Merge tuple validation and initialization of field maps in the tuple.
Make formats work for an incorrect tuple.
Make tuple_field() inline.

Use formats when creating tuples.
Store format id in the tuple.