Bottom-up tree mapping algorithm implementation

See #13, release log:

• 67543cb by @rultor: Merge branch '__rultor'
• e213ef5 by @kniazkov: Added and tested the main 'bui...
• 9c51dbd by @kniazkov: Mapping: create list of delete...
• fbf20ac by @kniazkov: Mapping partially mapped nodes
• 17568b7 by @kniazkov: Testing mapping with one delet...
• 67117d7 by @kniazkov: Mapping by identical hashes fr...
• 816c847 by @kniazkov: Mapping algorithm
• 96535f3 by @rultor: Merge branch '__rultor'
• 91af792 by @kniazkov: Stub test for mapper
• d3c4188 by @kniazkov: Depth algorithm
• 944c6c3 by @kniazkov: Porting hash calculation algor...
• 7140e8b by @kniazkov: Stub class for top-down mapper
• cbcc6c6 by @kniazkov: Added mapper interfaces
• 33f1a4b by @rultor: Merge branch '__rultor'
• 13fa933 by @kniazkov: CodeCov issue fixed (only one)
• e0c9e96 by @kniazkov: Method 'getAfter()' of diff no...
• 233bb90 by @kniazkov: Method 'getBefore()' of diff n...
• feaba88 by @kniazkov: Deserialization of trees with ...
• a7f7595 by @kniazkov: Added and tested 'deepCompare'...
• e8410d8 by @kniazkov: Some refactoring of diff tree ...
• and 14 more...

Released by Rultor 2.0-SNAPSHOT, see build log