First tenative implementation of error message change
note about the build-system patch for web permission issue on CentOS

over-the-shoulder (slack) review by mglukhovsky
Merge branch 'gchpaco_1600' into next
Add an internal datum_t::unchecked_get_pair() to optimize datum_t performance.
Use unchecked_get_pair() to implement get_pair()
Added a datum_t::unchecked_get() for arrays
Merge branch 'daniel_faster_datum_get_pair' into next
Merge branch 'next' into daniel_buf_ref_datum_2

Conflicts:
	src/rdb_protocol/datum.cc