Follow-up to #64.

- Removed NEW_SLIDER option, and use the skin "SliderStyle" instead.  Uses the new style by default, unless STYLE_PEPPYSLIDER is specified.
- Check if OpenGL 3.0 is supported before trying to draw new style sliders.
- Fixed compilation warnings; removed unneeded fields and imports.
- Filled in some missing Javadocs.
- Style changes.

Signed-off-by: Jeffrey Han <itdelatrisu@gmail.com>

src/itdelatrisu/opsu/Options.java

@@ -228,7 +228,6 @@ public class Options {
 				UI.getCursor().reset();
 			}
 		},
-		NEW_SLIDER("Enable New Slider", "Use the new Slider style (requires OpenGL 3.0).",false),
 		DYNAMIC_BACKGROUND ("Enable Dynamic Backgrounds", "The song background will be used as the main menu background.", true),
 		BACKGROUND_DIM ("Background Dim", "Percentage to dim the background image during gameplay.", 50, 0, 100),
 		FORCE_DEFAULT_PLAYFIELD ("Force Default Playfield", "Override the song background with the default playfield background.", false),
@@ -1072,9 +1071,6 @@ public class Options {
 					case "NewCursor":
 						GameOption.NEW_CURSOR.setValue(Boolean.parseBoolean(value));
 						break;
-					case "NewSlider":
-						GameOption.NEW_SLIDER.setValue(Boolean.parseBoolean(value));
-						break;
 					case "DynamicBackground":
 						GameOption.DYNAMIC_BACKGROUND.setValue(Boolean.parseBoolean(value));
 						break;
@@ -1226,8 +1222,6 @@ public class Options {
 			writer.newLine();
 			writer.write(String.format("NewCursor = %b", isNewCursorEnabled()));
 			writer.newLine();
-			writer.write(String.format("NewSlider = %b", GameOption.NEW_SLIDER.getBooleanValue()));
-			writer.newLine();
 			writer.write(String.format("DynamicBackground = %b", isDynamicBackgroundEnabled()));
 			writer.newLine();
 			writer.write(String.format("LoadVerbose = %b", isLoadVerbose()));