Simplified/corrected highlighted/selected appearance of feed and timeline cells.

- Set the highlighted text color on labels in table cells. This will be used
  for both the highlight and selected states automatically. (And since it is
  used for both states, we avoid anachronistic state where we have black
  text on a dark blue background in light mode as we transition from none ->
  highlighted -> selected.)

- Keep the selected/highlighted overrides to adjust colors for non-UIControl
  subelements.

iOS/MasterTimeline/Cell/MasterTimelineTableViewCell.swift

@@ -38,21 +38,31 @@ class MasterTimelineTableViewCell: NNWTableViewCell {
 		commonInit()
 	}
 	
+	override func applyThemeProperties() {
+		super.applyThemeProperties()
+
+		let highlightedTextColor = AppAssets.tableViewCellHighlightedTextColor
+		
+		titleView.highlightedTextColor = highlightedTextColor
+		summaryView.highlightedTextColor = highlightedTextColor
+		dateView.highlightedTextColor = highlightedTextColor
+		feedNameView.highlightedTextColor = highlightedTextColor
+	}
+	
 	override var frame: CGRect {
 		didSet {
 			setNeedsLayout()
 		}
 	}
 	
+	override func setHighlighted(_ highlighted: Bool, animated: Bool) {
+		super.setHighlighted(highlighted, animated: animated)
+		unreadIndicatorView.isSelected = isHighlighted || isSelected
+	}
+
 	override func setSelected(_ selected: Bool, animated: Bool) {
-		let selectedTextColor = selected ? AppAssets.selectedTextColor : UIColor.label
-		titleView.textColor = selectedTextColor
-		summaryView.textColor = selectedTextColor
-		dateView.textColor = selectedTextColor
-		feedNameView.textColor = selectedTextColor
-		unreadIndicatorView.isSelected = selected
-		
 		super.setSelected(selected, animated: animated)
+		unreadIndicatorView.isSelected = isHighlighted || isSelected
 	}
 
 	override func sizeThatFits(_ size: CGSize) -> CGSize {