Sidebar: Reformat trait tooltip

In the case of strong and resilient, the tooltip should now be easier
for players to understand.

Old:
	"+4 HP and +1 HP per level"

New:
	"+4 HP
	+1 HP per level"

Old:
	"battle axe and hammer: +1 damage and +1 HP"

New:
	"battle axe and hammer: +1 damage
	+1 HP"

src/units/unit.cpp

@@ -2326,7 +2326,9 @@ void unit::add_modification(const std::string& mod_type, const config& mod, bool
 			description += "\n";
 		}
 
-		description += utils::format_conjunct_list("", effects_description);
+		for(const auto& desc_line : effects_description) {
+			description += desc_line + "\n";
+		}
 	}
 
 	// store trait info