Parse transaction weights into blktxn_t structure

ABI break: sizeof(blktxn_t) has been increased, so accesses to blktmpl_t->txns[>0] use a different offset (aside, hash_ and txid are moved)
New ABI supports up to 512 MB transactions (with a max weight-per-bytes of 4), and library gracefully interprets larger weight values as -1 (unknown)

blkmaker_jansson.c

@@ -163,6 +163,15 @@ const char *parse_txn(struct blktxn_t *txn, json_t *txnj) {
 		}
 	}
 	
+	txn->weight = -1;
+	if ((vv = json_object_get(txnj, "weight")) && json_is_number(vv)) {
+		const double f = json_number_value(txnj);
+		const int32_t i32 = f;
+		if (f == i32) {
+			txn->weight = i32;
+		}
+	}
+	
 	// TODO: dependcount/depends, fee, required, sigops
 	
 	return NULL;

blktemplate.h

@@ -39,6 +39,7 @@ struct blktxn_t {
 	uint64_t fee;
 	bool required;
 	int16_t sigops;
+	int32_t weight;
 	
 	txnhash_t *hash_;
 	txnhash_t *txid;