Add limit setter

[mlee94]

Hi @nick-gorman,

I don't mean to overwhelm the PR log.

Thought we should add AEMO's interconnector limit setting logic in the interest of modelling AEMO's procedure (#24). Would be cool if we could run market.get_interconnector_limit_setter and retrieve the interconnector limits and their associated constraints.

The procedure is described in an old NEMMCO doc: https://aemo.com.au/-/media/files/electricity/nem/security_and_reliability/dispatch/policy_and_process/interconnector-limit-setter-reporting-changes.pdf

Before we move forward with unit tests, docstrings and examples, I would like to check that you find the namespaces (for new funcs) and structure acceptable, since you have pioneered this project. Still would like to add the FCAS limits for completeness.

[mlee94]

New public functions added, but they are a bit of a mouthful. Happy to update...

• market.get_interconnector_energy_constraint_limits:
  Full list of constraints and their associated limit on that interconnector direction (import or export).

• market.get_interconnector_energy_constraint_setter:
  Most restrictive constraint outlined in AEMO's process for an interconnector direction (energy only).

• market.get_interconnector_fcas_constraint_setter
  Most restrictive constraint outlined in AEMO's process for an interconnector direction (energy + fcas).

[mlee94]

Note, a number of unit tests will need to be rewritten if we include fcas_support_unavailable in the interconnector definitions (so that market.get_interconnector_fcas_constraint_setter can retrieve the data). But we could instead pass the fcas support data directly into market.get_interconnector_fcas_constraint_setter.