cleanup library and some basic tests. Includes, add guards to includes
diff --git a/include/polarssl/base64.h b/include/polarssl/base64.h
index 2da935b..6610a18 100644
--- a/include/polarssl/base64.h
+++ b/include/polarssl/base64.h
@@ -24,7 +24,7 @@
#ifndef POLARSSL_BASE64_H
#define POLARSSL_BASE64_H
-#include <string.h>
+#include <stddef.h>
#define POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL -0x002A /**< Output buffer too small. */
#define POLARSSL_ERR_BASE64_INVALID_CHARACTER -0x002C /**< Invalid character in input. */