Kgtool

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* refactor code, switch back to lowercase&underscore code style, split cns_schema into cns_model, cns_validate, cns_convert, cns_graphviz
* remove cns_creativework
* refactor cns_item validation logic and code
* add run_normalize_item, covert property value by schema template definition
* add stat_json_path, count json object for jsonpath, values, unique values, samples and value distribution
* rewrite validation code, update validation report

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* move cns.cns_schema to kgtool.cns_schema to better external access

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* change stats.py stat_table, reduce unique_counter's memory cost
* todo skip validate _Enum class validation
* change cns_organization change property names
* change cns_schema add lambda_key_cns_link for cns_link;
* change cns_schema skip generate alternateName when it is the same as name
* add stat_kg_summary summarize list of entity and relation and validate

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* change stat add "_value_" in stat entry
* add core.parseListValue
* add cns_excel, cns_schema for process excel based CnSchema
* cns_excel.task_excel2jsonld convert excel-based schema to JSON-LD version
* cns_schema with three main function cnsConvert, run_validate, run_graphviz

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* improve performance of stat

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* add core.any2sha256
* add table