Add methods for working with contacts. (#896)

Added methods for working with contacts:

* Import contact list
* Delete contact list
* Delete one contact

TLSharp.Core/TelegramClient.cs

@@ -234,6 +234,36 @@ namespace TLSharp.Core
             return (T)result;
         }
 
+        public async Task<TLImportedContacts> ImportContactsAsync(IReadOnlyList<TLInputPhoneContact> contacts)
+        {
+            if (!IsUserAuthorized())
+                throw new InvalidOperationException("Authorize user first!");
+
+            var req = new TLRequestImportContacts { Contacts = new TLVector<TLInputPhoneContact>(contacts)};
+
+            return await SendRequestAsync<TLImportedContacts>(req);
+        }
+
+        public async Task<bool> DeleteContactsAsync(IReadOnlyList<TLAbsInputUser> users)
+        {
+            if (!IsUserAuthorized())
+                throw new InvalidOperationException("Authorize user first!");
+
+            var req = new TLRequestDeleteContacts {Id = new TLVector<TLAbsInputUser>(users)};
+
+            return await SendRequestAsync<bool>(req);
+        }
+
+        public async Task<TLLink> DeleteContactAsync(TLAbsInputUser user)
+        {
+            if (!IsUserAuthorized())
+                throw new InvalidOperationException("Authorize user first!");
+
+            var req = new TLRequestDeleteContact {Id = user};
+
+            return await SendRequestAsync<TLLink>(req);
+        }
+
         public async Task<TLContacts> GetContactsAsync()
         {
             if (!IsUserAuthorized())

TeleSharp.TL/TLVector.cs

@@ -11,7 +11,17 @@ namespace TeleSharp.TL
     public class TLVector<T> : TLObject, IList<T>
     {
         [TLObject(481674261)]
-        private List<T> lists = new List<T>();
+        private List<T> lists;
+
+        public TLVector(IEnumerable<T> collection)
+        {
+            lists = new List<T>(collection);
+        }
+
+        public TLVector()
+        {
+            lists = new List<T>();
+        }
 
         public T this[int index]
         {