* move `common/port.h` to `includes/port.h`
* replace magic more magic numbers with constants
* artificially limit window size to 2^18 for quality 0 and 1
* use fixed shifts for quality 0 and 1 hashes
* removed `BrotliEncoderWriteMetadata`
* added `BROTLI_OPERATION_EMIT_METADATA` instead
* deprecated low-level API
* fixed MSVC warnings
* add Brotli*TakeOutput methods
* * flushing now doesn't require additional call
* add Brotli*Version methods
* moved public headers to 'public' directory
* removed C++ API
* do not assume STDC_VERSION is defined