iBUS on AUX Serial is working

- implemented iBUS
- updated the Tabs to spaces

.travis.yml

@@ -45,14 +45,13 @@ jobs:
       - export PATH=$HOME/arm-gcc-toolchain/bin:$PATH
       before_script: arm-none-eabi-gcc --version
 
-    # # Not yet supportted, see https://community.platformio.org/t/build-gd32-project-with-platformio/11944
-    # - name: platformio
-      # script: platformio run
-      # language: python
-      # python:
-      # - "2.7"
-      # install:
-      # - pip install -U platformio
-      # - platformio update
-      # cache:
-      # - directories: "~/.platformio"
+    - name: platformio
+      script: platformio run
+      language: python
+      python:
+      - "2.7"
+      install:
+      - pip install -U platformio
+      - platformio update
+      cache:
+      - directories: "~/.platformio"