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/ppp/polarssl/README

@@ -0,0 +1,22 @@
+About PolarSSL files into lwIP PPP support
+------------------------------------------
+
+This folder contains some files fetched from the latest BSD release of
+the PolarSSL project (PolarSSL 0.10.1-bsd) for ciphers and encryption
+methods we need for lwIP PPP support.
+
+The PolarSSL files were cleaned to contain only the necessary struct
+fields and functions needed for lwIP.
+
+The PolarSSL API was not changed at all, so if you are already using
+PolarSSL you can choose to skip the compilation of the included PolarSSL
+library into lwIP.
+
+If you are not using the embedded copy you must include external
+libraries into your arch/cc.h port file.
+
+Beware of the stack requirements which can be a lot larger if you are not
+using our cleaned PolarSSL library.
+
+
+PolarSSL project website: http://polarssl.org/