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.
Merge branch 'sam_2353' into sam_2353_ii
Merge branch 'sam_2353' into sam_2353_ii
Merge branch 'sam_2353' into sam_2353_ii
Moved cluster_version_t to containers/archive/versioned.hpp, unused (de)serialize_for_version functions.
Made mailbox/typed.hpp call deserialize_for_version.
Merge branch 'sam_2353' into sam_2353_ii
Fixed a bunch of "warnings" from a previous commit -- i.e. compilation errors.
Removed comment about renaming to archive_version_t.
Added cluster_version_t::LATEST_VERSION, ONLY_VERSION.
Moved around some assumption of local messages being serialized with the latest version.
Made send_message_write_callback_t::write take a cluster_version_t.
Made equivalent use of ONLY_VERSION in an applicable place.
Renamed connectivity_cluster_t::cluster_version to cluster_version_string.