cleanup library and some basic tests. Includes, add guards to includes
diff --git a/library/pkcs12.c b/library/pkcs12.c
index b992dba..f445955 100644
--- a/library/pkcs12.c
+++ b/library/pkcs12.c
@@ -38,6 +38,8 @@
 #include "polarssl/asn1.h"
 #include "polarssl/cipher.h"
 
+#include <string.h>
+
 #if defined(POLARSSL_ARC4_C)
 #include "polarssl/arc4.h"
 #endif