update Makefile with ztree.o
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Was not building properly without libsodium installed
Merge pull request #241 from hintjens/master

Was not building properly without libsodium installed
Allow libsodium to be installed in a custom path
Solaris/SmartOS fix for libsodium
Merge pull request #242 from mattconnolly/master

Allow libsodium to be installed in a custom path and fix for SmartOS/Solaris build
fix out of tree build
Merge pull request #243 from TTimo/master

fix out of tree build
Ensure zctx_destroy ignores NULL zockets, instead of asserting and failing
Merge pull request #244 from ulikoehler/fix-zocket-assert

Ensure zctx_destroy ignores NULL zockets, instead of asserting
Added mutex locking to zctx socket list
Add zmutex to assertions to check for nullptr mutexes
Remove mutex locking in zctx_destroy
Implemented zmutex_try_lock
On failed zlist_push, unlock before zmq_close
Merge pull request #245 from ulikoehler/zctx-sync

Synchronize zctx socket list access