fix: modAL.utils.__init__ fixed, functions added

Author: cosmic-cortex

modAL/utils/__init__.py

@@ -1,7 +1,11 @@
+from .combination import make_linear_combination, make_product, make_query_strategy
+from .data import data_vstack
 from .selection import multi_argmax, weighted_random
 from .validation import check_class_labels, check_class_proba
 
 __all__ = [
+    'make_linear_combination', 'make_product', 'make_query_strategy',
+    'data_vstack',
     'multi_argmax', 'weighted_random',
     'check_class_labels', 'check_class_proba'
 ]