VERSION 0.6.12: code cleanup in peers and IP address enumeration improvements

This version ties up some stuff that remains in the core before binary release.
It adds support for direct interface IP enumeration on *nix systems, as well
as a fix for IPv6 link-local addresses on OSX. This also contains some cleanup
in Peer and some improvements to help detect and route around dead or unreachable
supernodes.

Getting close!

version.h

@@ -41,6 +41,6 @@
 /**
  * Revision
  */
-#define ZEROTIER_ONE_VERSION_REVISION 11
+#define ZEROTIER_ONE_VERSION_REVISION 12
 
 #endif