Refactor distillation tasks to allow creation of DistillationTecher within Task. Add TokenDistillationTask.

Author: rwightman

timm/task/__init__.py

@@ -7,11 +7,14 @@
 from .task import TrainingTask
 from .classification import ClassificationTask
 from .distillation import DistillationTeacher, LogitDistillationTask, FeatureDistillationTask
+from .token_distillation import TokenDistillationTeacher, TokenDistillationTask
 
 __all__ = [
     'TrainingTask',
     'ClassificationTask',
     'DistillationTeacher',
     'LogitDistillationTask',
     'FeatureDistillationTask',
+    'TokenDistillationTeacher',
+    'TokenDistillationTask',
 ]