Merge pull request #166 from hintjens/master

Added zyre_uuid and fixed Win32 exports
Changing selftest to be done with default port 5670/udp
Merge pull request #169 from mvala/master

Changing selftest to be done with default port 5670/udp
Connection to subscriber is done only once now. Works for multiple subscribers. Fix for #168.
Fix typo in function declaration
Merge pull request #170 from mvala/master

Fix for #168.
Problem: discovery interval too high for wired LAN

Default setting is 1,000, which is OK for WiFi but too slow for wired
LAN, where UDP broadcast packets are very cheap.

Solution: expose this as zyre_set_interval() so calling application
can tune for specific use case. For wired LAN, 250 msec should be fine.
Simplified zyre_log_connect API

- afaics we don't need the separate methods for subscribers
- I switched to using a hash table for efficiency
- I removed the disconnect method, which was not orthogonal to
  connect, and doesn't solve any identified problem afaics
- some compile warnings removed along the way