0.13.0

Config methods are const
Added EncoderStringWriter to allow encoding directly to a String
EncoderWriter now owns its delegate writer rather than keeping a reference to it (though refs still work)
- As a consequence, it is now possible to extract the delegate writer from an EncoderWriter via finish(), which returns Result<W> instead of Result<()>. If you were calling finish() explicitly, you will now need to use let _ = foo.finish() instead of just foo.finish() to avoid a warning about the unused value.
When decoding input that has both an invalid length and an invalid symbol as the last byte, InvalidByte will be emitted instead of InvalidLength to make the problem more obvious.

0.12.2

A Read implementation (DecoderReader) to let users transparently decoded data from a b64 input source
IMAP's modified b64 alphabet
Relaxed type restrictions to just AsRef<[ut8]> for main encode*/decode* functions
A minor performance improvement in encoding

Minimum rust version 1.27.2
Fix bug in streaming encoding (#90): if the underlying writer didn't write all the bytes given to it, the remaining bytes would not be retried later. See the docs on EncoderWriter::write.
Make it configurable whether or not to return an error when decoding detects excess trailing bits.

Remove line wrapping. Line wrapping was never a great conceptual fit in this library, and other features (streaming encoding, etc) either couldn‘t support it or could support only special cases of it with a great increase in complexity. Line wrapping has been pulled out into a line-wrap crate, so it’s still available if you need it.
- Base64Display creation no longer uses a Result because it can't fail, which means its helper methods for common configs that unwrap() for you are no longer needed
Add a streaming encoder Write impl to transparently base64 as you write.
Remove the remaining unsafe code.
Remove whitespace stripping to simplify no_std support. No out of the box configs use it, and it's trivial to do yourself if needed: filter(|b| !b" \n\t\r\x0b\x0c".contains(b).
Detect invalid trailing symbols when decoding and return an error rather than silently ignoring them.

decode_config_slice function for no-allocation decoding, analogous to encode_config_slice
Decode performance optimization