Older versions of gcc do not support designated initializers.

Fixes 9a880ae6 ("Turn class Handler into struct space_vtab").

PackageCloud doesn't support Ubuntu Artful yet.

Follow up e3d97f6d

Closes #2805

The typo caused the following box.schema.user.info() failure if the user
was granted a permission to use a sequence:

  tarantool> box.schema.user.info()
  ---
  - error: 'builtin/box/schema.lua:1542: assign to undeclared variable ''seq'''
  ---

Class Handler contains only function pointers so we can easily convert
it to a C struct. This is needed to introduce internal C API to perfrom
DML requests on spaces which is required by SQL.

Needed for #2776

 - Engines should inherit struct space if they need to store engine
   specific data per space.
 - Engine::createSpace() now returns struct space instead of Handler.
 - Engines should overwrite Handler::destroy() to implement struct space
   destructor.

This is a step towards converting class Handler to struct space_vtab.

Needed for #2776

Currently, the format is stored in Handler and can be retrieved with
Handler::format(). The only reason for such a layer of indirection is
that the format should be created by an Engine method and currently it
is created by Engine::createSpace(). Let's introduce a separate method
for create a space format, Engine::createFormat(), and move the format
back to where it belongs, i.e. to struct space.

This is a step towards converting class Handler to struct space_vtab.

Needed for #2776

We gain no benefit from having them separated from corresponding
MemtxSpace::execute* methods.

This is a step towards converting class Handler to struct space_vtab.

Needed for #2776

space->handler->engine->... looks ugly. Since all Handler methods
receive space as an argument anyway, let's move engine to struct space.

This is a step towards converting class Handler to struct space_vtab.

Needed for #2776

Make new option in index part - collation - where user can pass
a name of a collation that he wants to use for comparison of the
field.

Fix #2649

Add a new space that contains collation definitions for future
index collation and more.

Add a collation cache for fast retrieving a collation object by
its name.

Needed for #2649

Introduce coll object that allows to compare strings.
Add coll_def structure and functions for its setup.
Add unit test.

Needed for #2649

Support [{field=<field_no>, type=<type>}, ...] index part format
both in box.space._index and box.schema.index.create() Lua API.

box.space_index now supports the following formats of index parts:

 1. <field_no>, <type>, <field_no>, <type>, ... -- Tarantool 1.6.0+
 2. [[<field_no>, <type>], ...] -- Tarantool 1.6.6+
 3. [{field=<field_no>, type=<type>}] -- Tarantool 1.7.6+, this patch

box.schema.upgrade() converts format #1 to #2. Format #2 is not converted
automatically to #3 yet. Let's extend box.schema.upgrade() to do that later
in order to keep upward compatibility for existing 1.7.x customers.

Lua API now supports the following formats:

1. [<field1_no>, <type1>, ,..] -- Tarantool 1.6.0+
2. [{field=<field_no>, type=<type>}] -- Tarantool 1.7.6+, this patch

In addition to format #2, [{<field_no>, type = <type>}] and
[<field_no>, <type>, may_be_added_in_the_future=xxx}] shortcut is supported.
box.schema.space.create() automatically converts format #1 to #2,
therefor all new indexes will have the new format.

Closes #2802

By some philosophic reasons it was decided to name functions
that deal with old format by name with a suffix - version of
tarantool when the format was initially introduced instead of
last version when this format was used.

Change type of 'map' argument to const char ** and return in it
the end of parsed msgpack map.

Move opt_def functions from alter.cc to opt_def.c.
Make no logical changes.

Headers duplicates are written in string separated with comma
Except special headers described in:
https://nodejs.org/api/http.html#http_message_headers

Relates to #2658

Fixes #2658

In a case of collision of field and method names, the field name have
higher priority.

Closes #1014

Aliases will allow to call tuple methods, when tuple has fields with
same names as methods. In such a case a field name has higher
priority and the tuple method with the same name becomes inaccessible
via tuple:...() API.

Needed for #1014

* Add package.search function
* Fix failing tests after patch for new loaders

Closes #2797

A patch by Alexander Turenko.

Fixes #2782

Closes #2639

It's unclear how to perform access checks in this case. Let's forbid it
explicitly until there's a user request for this feature.

- Fix the test case on macOS
- Replace os.execute("cp ...") with fio.symlink()
- Don't depend on files from other tests

Follow up #2767

- Add loader for current working directory
- Add loader for rocks searching in higher dirs like npm
- Remove rocks from `package.path` and `package.cpath`

Closes #2767

Since commit c0a30d17 ("sequence: speed up allocation of sequence
data tuple during checkpoint") sequence_data_iterator_next() does not
throw an exception, so the whole thing can be moved to sequence.c.

 - Add a new schema object class, 'sequence', which can be passed to
   box.schema.{grant,revoke} to grant access to a sequence.
 - To use a sequence (i.e. call next(), set(), or reset() on it), the
   user must either be the owner of the sequence or has a permission to
   write to it.
 - This also holds for sequences attached to spaces: the user can only
   insert a tuple to a space if he has a write access to the sequence
   attached to the space. UPDATE/DELETE do not require access to a
   sequence.
 - Automatically generated sequences are special: it can be used for
   auto increment (by passing nil to INSERT) even if the user was not
   explicitly granted access to it - it is enough to have write access
   to the space.

See #389

vy_index_validate_formats() check consistency of vy_index formats.
For example, all formats must have the same value of index_field_count
and mem_format must be equal to disk_format for the primary index.

Update disk_format for the primary key in the case when ALTER adds
a new space:format() field.

Extract struct tuple_field from field_def. Store field_def in space_def
and tuple_field in tuple_format.
It allows to do not store field names in tuple_format and do not
store binary offsets and internal flags in field definition
(specified by an user).