Subword-nmt

- multiprocessing support (get_vocab and apply_bpe)
- progress bar for learn_bpe
- seed parameter for deterministic BPE dropout
- ignore some unicode line separators which would crash subword-nmt

- BPE dropout (Provilkov et al., 2019)
- more efficient glossaries (https://github.com/rsennrich/subword-nmt/pull/69)

- fix to subword-bpe command encoding

- fix to subword-bpe command under Python 2
- wider support of --total-symbols argument

- segment_tokens method to improve library usability (https://github.com/rsennrich/subword-nmt/pull/52)
- support regex glossaries (https://github.com/rsennrich/subword-nmt/pull/56)
- allow unicode separators (https://github.com/rsennrich/subword-nmt/pull/57)
- new option --total-symbols in learn-bpe (commit 61ad8)
- fix documentation (best practices) (https://github.com/rsennrich/subword-nmt/pull/60)

- library is now installable via pip
- fix occasional problems with UTF-8 whitespace and new lines in learn_bpe and apply_bpe.
- do not silently convert UTF-8 newline characters into "\n"
- do not silently convert UTF-8 whitespace characters into " "
- UTF-8 whitespace and newline characters are now considered part of a word, and segmented by BPE