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.

Move struct key_def into an own header.
Rename key_def methods to follow the coding style.
Rename field_data_type to field_type.
Instead of panicking on key_def initialization
error, throw an exception.

The allocator consists of a common slab cache, region and slab
allocators.
The patch provides unit tests.

It also modifies rlist_shift to be more in line with the
rest of rlist functions.

Derive some tests for multipart HASH indexes
from the original implementation by A. Demakov
before dropping the branch.

Don't drop entire vardir on test suite start, it may have
symlinks, configuration files, etc. - useful for debugging.

1) Temporary result files weren't deleted, if test's skipcond failed.
2) Vardir is removed when tests started.
3) Sort tests and test-suites by name
4) Added cleanup to box/lua.test

* memcached/expirations.test
* memcached/flush-all.test
* replication/memcached.test

Remove trailing spaces. Get rid of an unused method.

1. sleep(0.1) -> sleep(0.01)
2. _server -> serv, _replica -> _repl.

2. Refactor find_tests code
3. Rewrite and Add comment for chdir(base) (test_run.py:145)
4. Rewrite .gitignore file for new name of unit tests