This commit will:
- Correct the constraints in PrefSubViewController.xib
- Change the Mirror setting to Never on the color wells in the XIB
- Change the language-direction of the battery icon from Fixed to Left
  to Right, Mirrors

This corrects a problem with color wells overlapping their labels on the
Subtitle tab of IINA's settings. This also changes the battery icon
shown in full screen mode to flip in a RTL language correcting another
overlapping problem.

This commit will:
- Correct the constraints in PrefSubViewController.xib
- Change the Mirror setting to Never on the color wells in the XIB
- Change the direction of the battery icon from Fixed to Both
- Add a reversed image to the battery icon
- Add a additionalInfoLabelXConstraint outlet to MainWindowController
- Add code to MainWindowController.windowDidLoad to adjust
  additionalInfoLabelXConstraint to center the label that provides the
  charge state when the battery icon is reversed

This corrects a problem with color wells overlapping their labels on the
Subtitle tab of IINA's settings. This also changes the battery icon
shown in full screen mode to flip in a RTL language correcting another
overlapping problem.