string: fix size of space needed for null terminator

Fix issue #322

There is a mistake in the unit test itself. The test make wrong
assumption that keys are ordered in the concurrent_hash_map. But
concurrent_hash_map is unordered associative container.

Wrong parameter is passed to constructor. When we create a new
node, the last parameter should be previous head. But in internal_copy()
method the b->tmp_node is passed by mistake.
Assert caught the issue on Windows. The assert is raised only when more
than one elements fit to the same bucket when we do internal_copy().

Merge back changes from stable-1.6

[1.6] Add option to force define IS_TRIVIALLY_COPYABLE

A typo fix.

Merge back changes from stable 1.6

Use libunwind

Change logic for finding font in pmpong example.

Klockwork fixes

Add option to disable hashmap

[1.6] string: fix max_size() return value

string: change sso_capacity so that sizeof(string) is always 32 bytes

(which is minimal possible size and equal to sizeof(vector)) and
change way of sso and large string detection.

common: fix Coverity skips with proper variable

[1.6] Add missing include to v.hpp.

Needed by std::forward_as_tuple.

common: correction of 'equal to' and quotation marks

New members order makes it possible to use union and exploit vector
_size member to store some additional information (e.g. on MSB).

Merge back changes from Stable 1.6

common: sort arguments alphanumerically in Dockerfiles

test: add iterator tests for string