This patch fixes some things missed in recent commits:
* insert attack sounds into maceman templates (D2855/rP24499 was rebased before D1354/rP24478 was committed)
* let Kushites start with an healer on (most) skirmish maps (D2843/rP24422 added them only to random maps)
* correct fortress tooltips (D1762/rP24393 gave fortresses a territory root, D2801/rP24470 removed champion cavalry and chariots from them)
* Rome siege walls are much narrower and lower than other walls and thus need smaller foundations (not done in D2502/rP23609)
* move the Ishtar Gate of Babylon out of the pers/ folder; it was built during the Neo-Babylonian Empire, i.e. predating the Persian Empire; Stonehenge isn't in the brit/ folder either (D2472/rP23888 removed it from the building lists)
* rename two unused icons (`barracks.png` → `military.png` and `ishtar_gate.png` → `bull.png`) to allow D2551 to rename their used counterparts (`pers_barracks.png` → `barracks.png` and `pers_gate.png` → `ishtar_gate.png`)
* insert placeholder icons in all free and autoresearched technologies that didn't have one already