Add OSX support, buildable via "make osx".
Make sure you have OpenSSL 1.0.0d+ (available from Macports) installed.

Based on diff from Vaibhav Bhembre via github
add osx and some flavor
remove commented out debug defines.
In kore_realloc() copy a minimum of old or new length bytes.
kore_buf_appendb(): free d once we are done with it.
remove meminuse and list of allocated memory blocks, we don't need it.
add IPv6 support and support for multiple listeners.
Resolving conflict with jorisvink/kore master