Fix SELECT vdbe to match tarantool data layout

Data layout in Tarantool is very different from SQLite's.
Consider the following DDL statements:

CREATE TABLE foo (a, b PRIMARY KEY, c)
CREATE INDEX fI  ON foo(a)
INSERT INTO  foo VALUES (
  (1, "one", "junk1")
  (2, "two", "junk2")
)

In SQLite, two BTrees are created:

foo / primary key! other fields / -
 one!1|junk1
 two!2|junk2

fI / index key! primary key / -
 1!one
 2!two

In Tarantool, data is stored with the field order matching
the DDL -
 1|one|junk1
 2|two|junk2

Each index yields data in the same very format.

The following changes were made:

 * fix field number in Column-s at VDBE generation time;
 * fix IdxLE/IdxLT/IdxGE/IdxGT for index keys spanning non-adjacent
   tuple fields in an arbitrary order;
 * tell optimizer that every index can provide every column in order to
   eliminate lookups into the primary index.