add function and class related with fp16 to runner/__init__.py (#448)

mmcv/runner/__init__.py

@@ -6,9 +6,10 @@ from .dist_utils import get_dist_info, init_dist, master_only
 from .epoch_based_runner import EpochBasedRunner, Runner
 from .fp16_utils import auto_fp16, force_fp32
 from .hooks import (HOOKS, CheckpointHook, ClosureHook, DistSamplerSeedHook,
-                    Hook, IterTimerHook, LoggerHook, LrUpdaterHook,
-                    MlflowLoggerHook, OptimizerHook, PaviLoggerHook,
-                    TensorboardLoggerHook, TextLoggerHook, WandbLoggerHook)
+                    Fp16OptimizerHook, Hook, IterTimerHook, LoggerHook,
+                    LrUpdaterHook, MlflowLoggerHook, OptimizerHook,
+                    PaviLoggerHook, SyncBuffersHook, TensorboardLoggerHook,
+                    TextLoggerHook, WandbLoggerHook)
 from .iter_based_runner import IterBasedRunner, IterLoader
 from .log_buffer import LogBuffer
 from .optimizer import (OPTIMIZER_BUILDERS, OPTIMIZERS,
@@ -28,5 +29,6 @@ __all__ = [
     'obj_from_dict', 'init_dist', 'get_dist_info', 'master_only',
     'OPTIMIZER_BUILDERS', 'OPTIMIZERS', 'DefaultOptimizerConstructor',
     'build_optimizer', 'build_optimizer_constructor', 'IterLoader',
-    'set_random_seed', 'auto_fp16', 'force_fp32'
+    'set_random_seed', 'auto_fp16', 'force_fp32', 'Fp16OptimizerHook',
+    'SyncBuffersHook'
 ]