number of application threads to use 0MQ sockets is unlimited; app_threads parameter in zmq_init is unused and obsolete

C and C++ headers moved from bindings/ to include/, bindings/ removed
--with-c and --with-cpp options to configure removed, C and C++ now built
and installed by default

configure.in is now the master source for the package version number,
this propagates to src/platform.hpp (for zmq_version) and doc/Makefile.am
(for documentation generation) automagically.

ZMQII-34: ensure that poll won't return POLLIN event when the message will be filtered out anyway (Win32)

ZMQII-34: ensure that poll won't return POLLIN event when the message will be filtered out anyway (POSIX)