Temporarily revert to old crypto code

(The new code is still segfaulting for me, and I'd like to proceed with other
work.)

This largely rolls back to the revision 1545 state of the existing code
(new crypto layer is still there with no callers), though I reintroduced
the segfault fix of revision 1562.

src/node.h

@@ -24,9 +24,7 @@
 #define __TINC_NODE_H__
 
 #include "splay_tree.h"
-#include "cipher.h"
 #include "connection.h"
-#include "digest.h"
 #include "list.h"
 #include "subnet.h"
 
@@ -52,9 +50,13 @@ typedef struct node_t {
 
 	node_status_t status;
 
-	cipher_t cipher;                        /* Cipher for UDP packets */
-	digest_t digest;                        /* Digest for UDP packets */	
-	int maclength;				/* Portion of digest to use */
+	const EVP_CIPHER *cipher;		/* Cipher type for UDP packets */
+	char *key;				/* Cipher key and iv */
+	int keylength;				/* Cipher key and iv length */
+	EVP_CIPHER_CTX packet_ctx;		/* Cipher context */
+	
+	const EVP_MD *digest;			/* Digest type for MAC */
+	int maclength;				/* Length of MAC */
 
 	int compression;			/* Compressionlevel, 0 = no compression */