New release with cross-verification vignettes

This is a much improved, simplified version, with highly improved performance, more consistent function interface and far more readable code.

• The Germany example is converted to the ESA2010 vocabulary.
• A completely new dataset, metadata and vignette was added to test the functions on the United Kingdom Input-Output Analytical Tables, 2010. article and dataset.
• The new function supplementary_add() can add a supplementary account or row to the table, useful to add employment data, for example.
• The new function total_tax_add() adds a summary of product and production taxes among the primary inputs.
• Clearly divided analytical functions, direct_effects_create() ,indirect_effects_create(), input_multiplier_create() create the direct, indirect and total effects matrix.