add static check

.drone.yml

@@ -8,6 +8,11 @@ platform:
   arch: arm
 
 steps:
+- name: static check
+  commands:
+  - cd gateway
+  - pio check -e pro-mini
+
 - name: native tests
   commands:
   - cd gateway

gateway/platformio.ini

@@ -8,6 +8,9 @@
 ; Please visit documentation for the other options and examples
 ; https://docs.platformio.org/page/projectconf.html
 
+[platformio]
+default_envs = pro-mini
+
 [env:pro-mini]
 platform = atmelavr
 board = miniatmega328
@@ -21,6 +24,10 @@ lib_deps =
 	adafruit/DHT sensor library@1.3.10
 build_flags = -D DHT_SENSOR=0
 upload_port = /dev/ttyUSB0
+check_tool = cppcheck
+check_flags = --enable=all
+check_skip_packages = yes
+check_severity = medium, high
 
 [env:native]
 platform = native

libraries/RF24

@@ -1 +0,0 @@
-Subproject commit cb04b381f9b68cf60cac7ecb18346fb3291a80a6