build: W600-SDK importiert, Firmware-Build und Hello am EVK

Docker-Build mit gcc-arm-none-eabi 4.9-2014q4 (statt Homebrew-Cask) verwendet,
Dockerfile/tools/docker.sh dafür aus Task 13 vorgezogen. cmake/sdk.cmake schont
gcc 4.9 (kennt -fcommon/-Wno-error=... nicht). Zwei zusätzliche SDK-Stubs
(EarlyInit, pre_gpio_config) in src/sys/sdk_stubs.c ergänzt, siehe sdk/PATCHES.md.

sdk/Src/Network/lwip2.0.3/netif/FILES

@@ -0,0 +1,24 @@
+This directory contains generic network interface device drivers that
+do not contain any hardware or architecture specific code. The files
+are:
+
+ethernet.c
+          Shared code for Ethernet based interfaces.
+
+ethernetif.c
+          An example of how an Ethernet device driver could look. This
+          file can be used as a "skeleton" for developing new Ethernet
+          network device drivers. It uses the etharp.c ARP code.
+
+lowpan6.c
+          A 6LoWPAN implementation as a netif.
+
+slipif.c
+          A generic implementation of the SLIP (Serial Line IP)
+          protocol. It requires a sio (serial I/O) module to work.
+
+ppp/      Point-to-Point Protocol stack
+          The lwIP PPP support is based from pppd (http://ppp.samba.org) with
+          huge changes to match code size and memory requirements for embedded
+          devices. Please read /doc/ppp.txt and ppp/PPPD_FOLLOWUP for a detailed
+          explanation.