Reformatted a comment.
Made blob::traverse_helper_t::preprocess return a buf_lock_t because C++11.
Added an integer-interval pmap function.
Replaced for loop traverse_index call with a pmap.
Removed the unused pimap function, simplified other pmap code.
Preparations for replacing rdb_erase_major_range().
Removed version numbers from serialization macros.
Removed some manually implemented serializer version information.
Remove some more manual implementations of serializer version numbers.
Removed versioning from seemingly the rest of the manually versioned serializers.
Removed VERSION_ERROR and manual wire_func_t serialization versioning.
Fixed a trailing whitespace line.
Made helper type mailbox_header_t.
Some irrelevant comment/whitespace/casting cleanup.
Added helper methods and types for comparing and manipulating clustner version numbers.
Computed version string into a resolve_version variable that is unused.
Improved a comment about cluster_version_string.
Passed a cluster_version_t through the on_message method.
Replaced rdb_major_erase and removed some related complications. Compiles except for unit tests.
Merge branch 'next' into daniel_2329

Conflicts:
	src/rdb_protocol/btree.cc
	src/rdb_protocol/store.cc
	src/unittest/rdb_btree.cc