Merge pull request #1275 from pmienk/master

Fix #1274
Problem: zmq_epgm is duplicate of zmq_pgm

There is zero benefit to this, and some confusion due to the special
case nature of this man page.

Solution: delete the zmq_epgm man page.
Merge pull request #1276 from hintjens/master

Problem: zmq_epgm is duplicate of zmq_pgm