Libpmemobj-cpp Version 1.5

This is the first release of libpmemobj-cpp as a separate project.

It introduces one persistent container - array, which has std::array
like interface. Currently it is considered experimental and lives
in experimental namespace.

We have also cleaned up some function names that, in retrospect, were
chosen poorly. Functions with old names are still there but are
deprecated.

Experimental features:

• volatile resides on pmem class
• persistent array container