Ability to alter one specified dataset.

• Adding insert functions for any type (except Query and hgqls_Literal)
• Adding delete function for any type (except Query and hgqls_Literal)
• Ensuring that schema altering mutations are permited
• Adding mutation handler
  • Type checking for each provided IRI (query and then compare to hgql schema)
  • Execution of the actual mutation
  • SelectionSet handover to query handler