Adding industry backup burner mix to external coupling

[kaskranenburgQ]

This PR adds the objectives of deliverable 3b in the ctm-etm coupling project. It consists of the following:

• Adding edges from the distribution nodes of the new input carriers for the node.
• Adding external coupling input statements for the new carriers.
• Adding hydrogen hourly calculation code to the backup burner.
• Adding external coupling input statements for the industry chp's.

[mabijkerk]

In a blank nl2019 scenario on this branch, with the inputs listed below, there is backup burner demand on the industry steam network, but the hydrogen_input_curve on the backup burner does not sum to the input_of_hydrogen. It does match for network gas.

external_coupling_industry_heat_backup_burner_wood_pellets_share: 20.0
external_coupling_industry_heat_backup_burner_coal_share: 20.0
external_coupling_industry_heat_backup_burner_gas_power_fuelmix_share: 20.0
external_coupling_industry_heat_backup_burner_hydrogen_share: 20.0
external_coupling_industry_heat_backup_burner_network_gas_share: 20.0
external_coupling_industry_heat_backup_burner_torrefied_biomass_pellets_share: 0.0
external_coupling_capacity_of_industry_chp_combined_cycle_gas_power_fuelmix: 0.0

EACH(
  SUM(V(industry_heat_backup_burner_network_gas,network_gas_input_curve))*MJ_PER_MWH,
  V(industry_heat_backup_burner_network_gas,input_of_network_gas),
  SUM(V(industry_heat_backup_burner_network_gas,hydrogen_input_curve))*MJ_PER_MWH,
  V(industry_heat_backup_burner_network_gas,input_of_hydrogen)
)

[
  17,282,228,770.03771,
  17,282,228,770.037415,
  15,161,083,112.028986,
  17,282,228,770.037415,
]