Added actual schema support to TabularDataParser. #826

examples/data/eln/example-schema.archive.yaml

examples/data/eln/example.excel.archive.xlsx

examples/data/eln/excel.archive.yaml

nomad/datamodel/context.py

nomad/datamodel/metainfo/eln/__init__.py

nomad/metainfo/metainfo.py

nomad/parsing/parsers.py

nomad/parsing/tabular.py

requirements.txt

tests/metainfo/test_metainfo.py

tests/parsing/test_tabular.py