Improve handling of arming, providing LED blink codes if the arming fails.

Also, implement a software watchdog to make sure that the main real-time
modules are actually being run. Provide a panic facility, also giving blink
codes to indicate the panic reason.

status.h

@@ -0,0 +1,36 @@
+/* status.h */
+
+#include "types.h"
+
+bool status_armed(void);
+void status_set_ready(unsigned int module, bool ready);
+void status_set_led_pattern(unsigned int module);
+void init_status(void);
+
+
+#define STATUS_MODULE_GYRO_ZERO 0
+#define STATUS_MODULE_GYRO_RATE 1
+#define STATUS_MODULE_ATTITUDE  2
+#define STATUS_MODULE_DCM_ERROR 3
+#define STATUS_MODULE_STICK     4
+
+#define STATUS_MODULES		5
+
+#define STATUS_COUNT {				\
+		STATUS_COUNT_GYRO_ZERO,		\
+		STATUS_COUNT_GYRO_RATE,		\
+		STATUS_COUNT_ATTITUDE,		\
+		STATUS_COUNT_DCM_ERROR,		\
+		STATUS_COUNT_STICK		\
+	}
+
+/*
+ * Each condition must be valid for so many samples, typically once
+ * per 100Hz loop
+ */
+#define STATUS_COUNT_STICK     100
+#define STATUS_COUNT_GYRO_ZERO 1
+#define STATUS_COUNT_GYRO_RATE 100
+#define STATUS_COUNT_ATTITUDE  100
+#define STATUS_COUNT_DCM_ERROR 100
+