Added custom errors, fixes to code generator

The code generator now handles okay the flags using True type
Also, double checking for the flag is now avoided in cases where the
flag was a Vector type

crypto/auth_key.py

@@ -1,6 +1,7 @@
 # This file is based on TLSharp
 # https://github.com/sochix/TLSharp/blob/master/TLSharp.Core/MTProto/Crypto/AuthKey.cs
 import utils
+from errors import *
 from utils import BinaryWriter, BinaryReader
 
 
@@ -11,7 +12,7 @@ class AuthKey:
         elif data:
             self.key = data
         else:
-            raise AssertionError('Either a gab integer or data bytes array must be provided')
+            raise InvalidParameterError('Either a gab integer or data bytes array must be provided')
 
         with BinaryReader(utils.sha1(self.key)) as reader:
             self.aux_hash = reader.read_long(signed=False)