db: expose layouts.

lib/bcoin/chaindb.js

@@ -268,6 +268,13 @@ function ChainDB(chain, options) {
 
 utils.inherits(ChainDB, AsyncObject);
 
+/**
+ * Database layout.
+ * @type {Object}
+ */
+
+ChainDB.layout = layout;
+
 /**
  * Open the chain db, wait for the database to load.
  * @alias ChainDB#open

lib/bcoin/txdb.js

@@ -264,6 +264,13 @@ function TXDB(wallet) {
   this.balance = null;
 }
 
+/**
+ * Database layout.
+ * @type {Object}
+ */
+
+TXDB.layout = layout;
+
 /**
  * Open TXDB.
  * @param {Function} callback

lib/bcoin/walletdb.js

@@ -201,6 +201,13 @@ function WalletDB(options) {
 
 utils.inherits(WalletDB, AsyncObject);
 
+/**
+ * Database layout.
+ * @type {Object}
+ */
+
+WalletDB.layout = layout;
+
 /**
  * Initialize wallet db.
  * @private