Expanded Techtree-Proto Connection for Accuracy, SpreadFactor, Max Spread and Building Work Rate

Expose ranged unit's accuracy, spread factor and max spread variables so that they can be modified by the Techtree files for use in technologies that can improve ranged unit accuracy.

Furthermore Building's BuildingWorkRate, which affects how a fast a protounit building can train, and research should also be exposed for modification by the techtree.