Adding the rest of files:

- ASM is disabled
- Neug needs full rewrite
- Flash is based on PiMoroni 4MB flash (needs adjust)

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>

shake256.h

@@ -0,0 +1,13 @@
+#include <stdint.h>
+
+struct shake_context {
+  uint64_t state[25];
+  uint32_t index;
+};
+typedef struct shake_context shake_context;
+
+void shake256_start (struct shake_context *shake);
+void shake256_update (struct shake_context *shake,
+		      const unsigned char *src, unsigned int size);
+void shake256_finish (struct shake_context *shake,
+		      unsigned char *dst, unsigned int size);