add swift wrapper methods to add and open an encrypted account db

DcCore/DcCore/DC/Wrapper.swift

@@ -23,6 +23,10 @@ public class DcAccounts {
         return Int(dc_accounts_migrate_account(accountsPointer, dbLocation))
     }
 
+    public func addClosedAccount() -> Int {
+        return Int(dc_accounts_add_closed_account(accountsPointer))
+    }
+
     public func add() -> Int {
         return Int(dc_accounts_add_account(accountsPointer))
     }
@@ -119,6 +123,15 @@ public class DcContext {
         return swiftString
     }
 
+    // The passphrase can be ommited if the account db is not encrypted
+    public func open(passphrase: String? = nil) {
+        dc_context_open(contextPointer, passphrase)
+    }
+
+    public func isOpen() -> Bool {
+        return dc_context_is_open(contextPointer) == 1
+    }
+
     // viewType: one of DC_MSG_*
     public func newMessage(viewType: Int32) -> DcMsg {
         let messagePointer = dc_msg_new(contextPointer, viewType)