allow XSUB/XPUB to send/recv messages unrelated to sub/unsub (LIBZMQ-490)

zmq::xpub_t::xread_activated() – change to process messages without 0
or 1 prefix, but without affecting subscriptions

zmq::xsub_t::xsend() – change to send rather than discard messages
without 0 or 1 prefix, but without affecting subscriptions

Update documentation
Merge pull request #494 from jgm-radez/master

allow XSUB/XPUB to send/recv messages unrelated to sub/unsub
Test cases were failing on bind
Removed use of deprecated API methods
Spelling fixes
Specified that it's safe to call zmq_msg_more after zmq_msg_close
Clarification on zmq_msg_more
Old change to move ports off 5555 (was conflicting with other stuff)
Whitespace and comment fixes
Revert "Test cases were failing on bind"

This reverts commit 8ba097f3da8d1a752755a52b1d3ec967c23f0643.
Revert "Old change to move ports off 5555 (was conflicting with other stuff)"

This reverts commit da0efaa81771aba497a961d70f2166f500a52afd.
Merge pull request #495 from hintjens/master

Whitespace and comment cleanups
Fixed el5/el6 deps in RPM spec file
Fixed newline in test_disconnect_inproc
Merge pull request #496 from amuraru/master

Fixed el5/el6 deps in RPM spec file / newline fix
Clarified zmq_bind on icp://
Merge pull request #497 from hintjens/master

Clarified how icp:// works with zmq_bind
deprecate zmq_ctx_destroy in favor of zmq_ctx_term

in order to avoid logical collisions with pre-existing notions of context destruction in bindings (czmq, pyzmq).
move configure.in -> configure.ac

autotools warns that configure.in
should actually be named configure.ac
AM_CONFIG_HEADER -> AC_CONFIG_HEADERS

AM_CONFIG_HEADER raises an 'obsolete error' with automake 1.13.