Features
- Add constant_ and orthogonal_
- Add Linear and ConjugatedLinear
- Add Projector and ConjugatedProjector
- Add optimizer Aku interfaces, i.e., SGD and Adam
- Add scheduler Aku interfaces, i.e., InverseDecay and Fixed
- Add GTU activation function
- Add SizedBatchSampler to support customized batch size
- Add meters, i.e., AverageMeter, AccuracyMeter, ClassificationMeter, and TimeMeter
- Add hooks, i.e., summary, load_checkpoint, save_checkpoint
- Add naive pipe for contextual word representation, i.e., CtxPipe