Managing resource and building

[already merged from master. Should not have problem when merging]

Creates GameResourceManager in manager package that manages all resources in the game. Manages to allocate resources and "destroy" resources properly after gathered.
(The original ResourceManager is renamed into IndividualResourceManager to differentiate)

Creates GameBuildingManager in manager package that manages all buildings in the game. Manages to assign building products to the corresponding player. Also supports OccupyStrategy for reassigning building.

features(gather, assign, destroy resources; assign building products) work on StartGUI.