Separated the uIP makefile from the top-level Makefile.include into a separate core/net/Makefile.uip makefile
Added #if UIP_CONF_IPV6 around the IPv6 code in the uIP source tree to allow the C files to be compiled even if IPv6 is not configured.
Merge pull request #173 from adamdunkels/feature-ipv6-not-in-makefile

Allow IPv6 to be compiled via #define