Treevalue

What's Changed
* feature(hansbug): Add __version__ to treevalue module by HansBug in https://github.com/opendilab/treevalue/pull/7
* fix(hansbug): fix bug when missing is used on the whole non-existing child tree by HansBug in https://github.com/opendilab/treevalue/pull/11
* feature(hansbug): add flatten and unflatten to support parallel calculation. by HansBug in https://github.com/opendilab/treevalue/pull/9
* dev(hansbug): add get_or_default method to test_storage by HansBug in https://github.com/opendilab/treevalue/pull/13
* dev(hansbug): add support for debugger in TreeValue class by HansBug in https://github.com/opendilab/treevalue/pull/12
* dev(hansbug): optimize for TreeValue's getattr by HansBug in https://github.com/opendilab/treevalue/pull/16
* dev(hansbug): refactor all the __ixx__ operators by HansBug in https://github.com/opendilab/treevalue/pull/15
* test(hansbug): add benchmark for the basic operations and functions by HansBug in https://github.com/opendilab/treevalue/pull/14
* doc(hansbug): update documentation for mapping and filter_ && update README's demo by HansBug in https://github.com/opendilab/treevalue/pull/17


**Full Changelog**: https://github.com/opendilab/treevalue/compare/v1.0.0...v1.1.0

Great optimize by using cython.

**Full Changelog**: https://github.com/opendilab/treevalue/compare/v0.1.0...v1.0.0

Add plenty of new features (in issue 2):

* Dump of the tree value graph.
* Suport pickle.dumps of TreeValue objects
* Binary-based full data dump
* Binary-based full data load
* Native-python-based full data load
* Self calculation with original address
* Self operator with original address
* Add more features in general_treevalue, such as NotImplement
* CLI support (dump/load, graph generation, graphviz code dump, etc)

Documentation for new version (in issue 4): https://opendilab.github.io/treevalue/v0.1.0/

First version of treevalue, cheers!