client/tarantool: proper error display

test/connector_c: sql select limit test
client/tarantool: error processing fix

Continue improving valgrind run: add recommended luajit suppressions.

Workaround a valgrind warning in strtod on 64 bit systems.

On 64-bit systems, strtod uses an optimized version of
strcasecmp to find out whether or not a string represents
a number.

This version uses int (8 byte) comparison. If the string
in turn is less than 8 bytes, or is not aligned around 8 byte
boundary, uninitialized memory can be accessed.

Work this around with a simple test (this is lame and
incomplete, but covers our cases. In future either
this in valgrind will be gone, or our code will change,
or we add a suppression).

Fix a valgrind warning in sptree.h discovered by new tests.

test/connector_c: tnt_reply test added

Rewrite addr2symbol binary search: make it simpler,
fix bugs with access to symbols[-1], make sure it works
correctly on 64 bit systems (s/int/ssize_t).

Add a way to do nested iteration in Lua stored procedures.
Implement destruction for tree indexes and iterators.
This clears a few valgrind warnings.

Fix connector_c test.

Finish porting index API to objective C.
Change all methods to become objective C methods.
Implement a family of virtual constructors and destructors.
Change iterator allocation scheme.

tnt_stream_reqid()

Use the index iterator API in memcached.m,
instead of hard-coded access to index internals,
which broke index abstraction.

This (temporarily) can (somewhat) break expire
in presense of SELECT command against memcached namespace,
since SELECT uses the same iterator.

Hopefully, it's only temporary, since we'll soon
be able to have more than one independent generic iterator
over the same index.

Do not pre-allocate Index object.

Fix valgrind errors.

A pre-requisite patch for turning Index into an Object:

Extract key description into an own structure, struct key.

Introduce key_config function, which
transfers configuration from confetti structure
into struct key.

This allows to decouple index construction from
key construction -- something you need
if you want a virtual constructor for index.

SHOW INFO now prints path to config
Review Dmitry's patch, fix tests.