Minor cosmetic tuning

Switching the numeric seed labels to a colon formatting makes it more consistent with both the text seed label and the world type label (displayed together in SeedAndWorldTypeWidget)

src/main/java/amidst/gui/main/viewer/widget/SeedAndWorldTypeWidget.java

@@ -15,7 +15,7 @@ public class SeedAndWorldTypeWidget extends ImmutableTextWidget {
 	@Override	
 	protected int getLineSeparationHeight(FontMetrics fontMetrics) {
 		// Add some extra line spacing because the seed and world type
-		// are separate items, rather than multi-line text.
-		return (int) Math.round(super.getLineSeparationHeight(fontMetrics) * 1.3);
+		// are separate items, rather than multi-line paragraph text.
+		return (int) Math.round(super.getLineSeparationHeight(fontMetrics) * 1.2);
 	}		
 }

src/main/java/amidst/gui/main/viewer/widget/SelectedIconWidget.java

@@ -19,7 +19,7 @@ public class SelectedIconWidget extends IconTextWidget {
 			WorldIconSelection worldIconSelection) {
 		super(anchor);
 		this.worldIconSelection = worldIconSelection;
-		increaseYMargin(80);
+		increaseYMargin(65);
 	}
 
 	@CalledOnlyBy(AmidstThread.EDT)

src/main/java/amidst/mojangapi/world/WorldSeed.java

@@ -24,7 +24,7 @@ public class WorldSeed {
 			if (this == TEXT) {
 				return labelPrefix + ": '" + text + "' (" + seed + ")";
 			} else {
-				return labelPrefix + " (" + seed + ")";
+				return labelPrefix + ": " + seed;
 			}
 		}
 	}