Implement changes related to datapackage version 2

[pierrecamilleri]

This issue gives information to track the adaptation of frictionless-py to the version 2 of the datapackage specification.

Right now, no single feature of datapackage v2 has been implemented in frictionless-py , but hopefully we will be working on this soon. I'll keep this issue up to date as soon as the developments become more concrete.

• Tabular Data Package (removed)
• package.$schema (new)
• package.contributors (updated)
• package.version (updated)
• package.sources (updated)
• resource.name (updated)
• resource.path (updated)
• resource.type (new)
• resource.$schema (new)
• resource.encoding (updated)
• resource.sources (updated)
• dialect.schema (new)
• dialect.table (new)
• schema.$schema (new)
• schema.fieldsMatch (new)
• schema.missingValues (updated)
• schema.primaryKey (updated)
• schema.uniqueKeys (new)
• schema.foreignKeys (updated)
• field.categories (new)
• field.categoriesOrdered (new)
• field.missingValues (new)
• integer field type (updated)
• list field type (new)
• datetime field type (updated)
• geopoint field type (updated)
• any field type (updated)
• minimum and maximum field constraints (updated)
• exclusiveMinimum and exclusiveMaximum field constraints (new)
• jsonschema field constraint (new)

[ezwelty]

A great starting point is the list in the changelog at https://datapackage.org/overview/changelog/#v20