Added zframe_sendmem + zero-copy version + tests
Make zsockopt_set_subscribe, ..._unsubscribe and ..._identity take a const char* argument
Update doc/zsockopt.txt
Merge pull request #157 from ulikoehler/zframe_sendmem

Added zframe_sendmem + zero-copy version + tests
Merge pull request #160 from ulikoehler/zsockopt_const_subscribe

Make zsockopt_set_... take const char* args