Correct rx channel min/max pulse checking so that it is inclusive to

match the documentation.  Add first unit tests for code in rx.c.

src/test/unit/platform.h

@@ -27,3 +27,21 @@
 #define SERIAL_PORT_COUNT 4
 
 #define MAX_SIMULTANEOUS_ADJUSTMENT_COUNT 6
+
+typedef enum
+{
+    Mode_TEST = 0x0,
+} GPIO_Mode;
+
+typedef struct
+{
+    void* test;
+} GPIO_TypeDef;
+
+typedef struct
+{
+    void* test;
+} TIM_TypeDef;
+
+typedef enum {DISABLE = 0, ENABLE = !DISABLE} FunctionalState;
+