select contiguous data splits for val and train (#200)

* select contiguous data splits for test and train

* changed data-dir to data_dir as arg to prepare_dutchf3.py

* update script with new required parameter label_file

* ignoring split_alaudah_et_al_19 as it is not updated

* changed TEST to VALIDATION for clarity in the code

* included job to run scripts unit test

* Fix val/train split and add tests

* adjust to consider the whole horz_lines

* update environment - gitpython version

scripts/prepare_dutchf3.py

@@ -39,7 +39,8 @@ def _write_split_files(splits_path, train_list, val_list, loader_type):
     file_object = open(path.join(splits_path, loader_type + "_train_val.txt"), "w")
     file_object.write("\n".join(train_list + val_list))
     file_object.close()
-    file_object = open(path.join(splits_path, loader_type + "_train.txt"), "w")
+    file_object = open(path.join(splits_path,
+                       loader_type + "_train.txt"), "w")
     file_object.write("\n".join(train_list))
     file_object.close()
     file_object = open(path.join(splits_path, loader_type + "_val.txt"), "w")