v0.1.91

New API

• [Python] Added a feature to feed training data as Python's iterable object.
  https://github.com/google/sentencepiece/tree/master/python#training-without-local-filesystem
• [Python] Added a feature to set model writer to emit the output model to any non-local devices.
  https://github.com/google/sentencepiece/tree/master/python#training-without-local-filesystem
• [C++] Add an API to returns the trained model directly as std::string.

Bug Fix

• Ignores nbest parameter in BPE-dropout
• fixed build error when SPM_ENABLE_NFKC_COMPILE=ON
• fixed the cost computation around user_defined_symbol and faster encoding introduced in the previous release.