Changes

Added CheckBoxListener for GuiAdvancedCheckBox

Made GuiVideoFramerateSlider a subclass of GuiAdvancedButton and added missing @Override annotations

ComposedElement initially sorts its elements and respects their elements' y position if both are Dropdowns

Made GuiColorPicker a subclass of GuiAdvancedButton and call pickerToggled() method from own click handler methods

added getWidth() method to GuiString which returns the width of the drawn String (calculated using FontRenderer#getStringWidth())

Added more Constructors to GuiAdvancedTextField

Right-Clicking a Position Keyframe teleports the Camera to that Keyframe's Position, Right-Clicking a Time Keyframe jumps to its Timestamp | https://trello.com/c/dL48nHyG/
DRYed closest Keyframe calculation on GuiKeyframeTimeline
DRYed closest Keyframe calculation on GuiMarkerTimeline

Made GuiReplaySpeedSlider a subclass of GuiAdvancedButton

Created dummy GuiOverlayElement interface for ComposedElement to determine which Elements to draw last
Added methods to retrieve position and size from a GuiElement
Added draw() method with option to override hovered boolean to GuiElement interface and implemented it. This is required for GuiAdvancedButtons which would be tinted blue (as if hovered) even though an overlying GuiElement (e.g. GuiDropdown) was hovered

GuiColorPicker#hoveringPicker only returns true if the GuiElement is enabled

Reduced Constructor sets GuiAdvancedTextField's height

Rewrote GuiRenderSettings to use the semi-new Gui System and have three instead of two pages (Video Settings, Advanced Settings, Command Line Settings)