Add main method

.gitignore

 .DS_Store
 *.o
+build

src/main.c

+/*
+ * main() method
+ */
+
+#include "spi.h"
+#include "timer.h"
+#include "rx.h"
+
+void main(void) {
+    timerInit();
+    spiInit();
+    rxInit();
+
+    for(;;) { }
+}
+