Revert "Make FD_SETSIZE = ZMQ_MAX_SOCKETS_DFLT + 1 so there is room for the repear socket."

This reverts commit 0b92831b2a82c3bbc0e9371662c546b94915a3ea.
Reduce default maximum number of sockets by 1 so there is room for the reaper socket.
Fix signed/unsigned comparison
Fix signed/unsigned comparison
Merge pull request #752 from ricnewton/master

Revert "Make FD_SETSIZE = ZMQ_MAX_SOCKETS_DFLT + 1 so there is room for ...