python-v0.3.0

Changes:

• BPETokenizer has been renamed to CharBPETokenizer for clarity.
• Added CharDelimiterSplit: a new PreTokenizer that allows splitting sequences on the given delimiter (Works like .split(delimiter))
• Added WordLevel: a new model that simply maps tokens to their ids.
• Improve truncation/padding and the handling of overflowing tokens. Now when a sequence gets truncated, we provide a list of overflowing Encoding that are ready to be processed by a language model, just as the main Encoding.
• Provide mapping to the original string offsets using:

output = tokenizer.encode(...)
print(output.original_str.offsets(output.offsets[3]))

• Exposed the vocabulary size on all tokenizers: https://github.com/huggingface/tokenizers/pull/99 by @kdexd

Bug fixes:

• Fix a bug with IndexableString
• Fix a bug with truncation