This commit is a significant overhaul of the library in an effort to head
towards a stable API. The rope implementation as well as a number of buffer
implementations have been removed from the library and will live at
https://github.com/carllerche/bytes-more while they incubate.
**Bytes / BytesMut**
`Bytes` is now an atomic ref counted byte slice. As it is contigous, it offers
a richer API than before.
`BytesMut` is a mutable variant. It is safe by ensuring that it is the only
handle to a given byte slice.
**AppendBuf -> ByteBuf**
`AppendBuf` has been replaced by `ByteBuf`. The API is not identical, but is
close enough to be considered a suitable replacement.
**Removed types**
The following types have been removed in favor of living in bytes-more
* RingBuf
* BlockBuf
* `Bytes` as a rope implementation
* ReadExt
* WriteExt
- This fixes#25 and fixes#26.
- Move the mark state into a 'Mark' enum.
- Store both 'pos' and 'len' inside the mark because both
are needed to distinguish between full/empty states. This
fixes 'reset' setting 'len' to zero when the buffer was
full when marked.
- Clear the mark when the length of the marked input range
exceeds the capacity. Fixes bugs with the mark not being
cleared correctly on writes.
- Add test cases.
Carl Lerche