Keyvi

- fixed a memory leak in SerializationUtils (164)

- added `get_all_items` bindings to Rust (161)
- updated utfcpp - 3rdparty utf8 utils (158)
- updated examples to python 3 (159)
- formatted rust code with `cargo fmt` (162)

**Fixes**

- fix race condition in index when concurrently accessing same segment (154)
- fix overflow in distance calculation (156)

- dropped most module imports from global `keyvi` namespace, from now on only submodule imports are supported 147
- using package `msgpack` instead of `msgpack-python`: for more details regarding compatability see [here](https://github.com/msgpack/msgpack-python#pypi-package-name) 145
- rust bindings now support return of internal `msgpack` value 146

**New and Noteworthy**

- packages for python 3.8
- lots of keyvi index improvements, keyvi index is now usable as "beta" feature (usable, limited in functionality)
- fuzzy completion overhaul

**Breaking changes**

- drop support for python 2.7 and 3.4
- drop manylinux 1 packages in favor of manylinux 2014, older distributions might not be supported anymore
- drop support for macOS 10.11, 10.12, macOS 10.13 is now the minimum

- Refactoring of value types (93)
- Bugfixes (100, 103)
- Note that issue 96 still remains open