Refactor orders menu to its own set up method. Add build city menu item. Add enabling of build city when own engineer in selected stack. Remove extra add(resource_panel). Add build city window, done everything except actually building selected city. BUGFIX introduce C.HARVEST_TERRAIN_ORDER to look for trees before hills and mountains during harvesting.
Enable actual building of selected city in build city panel.
Fix enabling of build city menuitem so that it is selectable only when a stack on a planet is selected and the stack contains an engineer.
Calculation of move cost uses Math.ceil instead of Math.floor to produce move costs consistent with EFS.