add primary energy carrier classes

[akleinau]

closes #77

adds classes:

• primary energy production as subclass of process: Primary energy production is a process that prepares raw material for its use as primary energy carrier.
• primary energy carrier mining as subclass of primary energy production: primary energy carrier mining is a primary energy production process that recovers non-renewable energy carriers from its natural site.
• primary energy carrier harvest as subclass of primary energy production: primary energy carrier harvest is a primary energy production process that collects solid biomass from its natural site.