Adds a new component Upkeep similar to ResourceTrickle but to allow for entities costing resources instead of providing them.
A separate component because:
- ResourceTrickle is not suited for negative rates and the adaptation thereof would make it unnecessary complex.
- "We" may want to introduce effects to happen when upkeep cannot be paid.
This is semi-WIP since there is no penalty for not having the needed amount of resources besides being spammed by "Insufficient resources"-messages. That message should be altered (more specific to upkeep) or at least improve UX for that.
Ideas for penalties of not being able to provide the necessary resources include:
- Decline of HP.
- Conversion of CP to GAIA.
- Reduced effectiveness of the entity (e.g. workrate, attackpower, productionrate).