Uupdate GSL referenece in packaging script.
Assertion failure in zsockopt.c:965

zsocket_set_linger: Assertion `rc == 0 ... ' failed.

Caused by using zctx_t type for global_context, so that it was trying
to shut down sockets the old way on process exit.

Solution: move global context creation/shutdown to zsys, and use plain
zmq context reference.

Note: this plus new zactor class will result in deprecated classes:
zctx, zmutex, zthread, zsocket, zsockopt.
Initial empty zactor class
Trivial comment fix
Added builds/msvc and packaging/ to source packages

Fixes #464
Allow CZMQ code to use zmq_ctx_new/term

Needs macro to backport these to libzmq/2.x
Adding zmq_ctx_init/term support for libzmq/3.x
Don't install test binaries into bindir
Merge pull request #465 from hintjens/master

Fixed #464, other changes
Updated libzmq imports to include gssapi.
Added zsys_run_as () method

Drops PID into lockfile and optionally switches to specified
group/user. Ideal in combination with zsys_daemonize ().
Merge pull request #467 from hintjens/master

Added zsys_run_as () method
Fix trying to save zconfig_t to non-existant path
Merge pull request #468 from phuedx/master

Fix trying to save zconfig_t to non-existant path
zconfig_chunk_save will now save the wole config (sub)tree instead of just one config entry
Merge pull request #470 from xaqq/zconfig_chunk_save

Fix zconfig_chunk_save's abort and save the tree instead of the first entry.
Updated libsodium imports.
Consolidate shared VS props across versions.
Batched VS builds.
Merge pull request #471 from evoskuil/master

Batch VS builds, consolidate shared props, update imports