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.
Cleanup and refactoring of the STM32w port

This is a general cleanup of things like code style issues and code structure of the STM32w port to make it more like the rest of Contiki is structured.
Merge pull request #173 from adamdunkels/feature-ipv6-not-in-makefile

Allow IPv6 to be compiled via #define
Merge pull request #175 from adamdunkels/feature-updated-stm32w

Cleanup and refactorization of the STM32w port
Merge branch 'master', remote-tracking branch 'upstream/master'