Never use lstm

Refs #133 (closed)

dan/ocr/document/train.py

@@ -153,7 +153,6 @@ def get_config():
             "dec_dim_feedforward": 256,  # number of dimension for feedforward layer in transformer decoder layers
             "use_2d_pe": True,  # use 2D positional embedding
             "use_1d_pe": True,  # use 1D positional embedding
-            "use_lstm": False,
             "attention_win": 100,  # length of attention window
             # Curriculum dropout
             "dropout_scheduler": {