Added a watchtower set piece variation for the medieval through industrial eras. Added ARTERA_SAILOR_POSTANTIQUE to facilitate this. Thanks to JNR for his advice. Changed to a smaller base obstruction profile, which allowed for the following: Removed manual clutter items from the bases for forest, jungle, and marsh. Consolidated jungle and forest improvements into a single improvement. Differences were negligible without the need for manual clutter. Consolidated snow and tundra improvements into a single improvement. Colonel Snowman is on both. Added machine-translated language support for Italian, Korean, Polish, Portuguese, and Spanish. Pruned unneeded assets
