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.

config.local.cmake.example

@@ -0,0 +1,8 @@
+# Copy to config.local.cmake (gitignored) and adjust.
+# set(NINLIGHT_TOKEN "change-me-please")
+# Used from plan 2 on:
+# set(NINLIGHT_WIFI_SSID "MyWifi")
+# set(NINLIGHT_WIFI_PASSWORD "secret")
+# set(NINLIGHT_AP_PASSWORD "ninlight")
+# Used from plan 3/4 on (path to the old RSA signing key):
+# set(NINLIGHT_MIGRATION_KEY "/path/to/fw_sign.pem")