Merge pull request #3562 from wlemkows/pobj-arena-id-flag

doc/libpmemobj/pmemobj_action.3.md

doc/libpmemobj/pmemobj_alloc.3.md

doc/libpmemobj/pmemobj_ctl_get.3.md

doc/libpmemobj/pmemobj_tx_alloc.3.md

src/include/libpmemobj/action_base.h

src/include/libpmemobj/base.h

src/include/libpmemobj/tx_base.h

src/libpmemobj/heap.c

src/libpmemobj/heap.h

src/libpmemobj/list.c

src/libpmemobj/obj.c

src/libpmemobj/obj.h

src/libpmemobj/palloc.c

src/libpmemobj/palloc.h

src/libpmemobj/pmalloc.c

src/libpmemobj/tx.c

src/test/obj_ctl_arenas/TEST3

src/test/obj_ctl_arenas/TEST3.PS1

src/test/obj_ctl_arenas/TEST4

src/test/obj_ctl_arenas/TEST4.PS1