Extend technology manager for template data

[historic_bruno]

The new tech system currently supports applying stat modifications to existing entities. But we often need the stats prior to creating the entity, for information/UI or e.g. using costs to calculate if we have sufficient resources to create the entity. Maybe we can split template access (as in GuiInterface.GetTemplateData()) into multiple functions, like GetBaseTemplateData() for the unmodified base stats, GetBonusTemplateData() for the tech bonuses, and GetCombinedTemplateData() for the combined data. The bonus values would be most useful for UI and only have meaning for numeric values like attack/armor/LOS.

I guess something similar is needed for AIs.