Added PathPreviewRenderer to draw a Preview of the current Camera Path into the World

Added KeyframesModifyEvent to be dispatched whenever the ReplayHandler's Keyframe List is changed
Refactored Event package
Reworked Settings GUI

src/main/java/eu/crushedpixel/replaymod/gui/elements/GuiOnOffButton.java

@@ -0,0 +1,24 @@
+package eu.crushedpixel.replaymod.gui.elements;
+
+import net.minecraft.client.resources.I18n;
+
+public class GuiOnOffButton extends GuiToggleButton {
+
+    private static final String[] values = new String[] {I18n.format("options.on"), I18n.format("options.off")};
+
+    public GuiOnOffButton(int buttonId, int x, int y, String buttonText) {
+        super(buttonId, x, y, buttonText, values);
+    }
+
+    public GuiOnOffButton(int buttonId, int x, int y, int width, int height, String buttonText) {
+        super(buttonId, x, y, width, height, buttonText, values);
+    }
+
+    public GuiOnOffButton(int buttonId, int x, int y, int width, int height, String buttonText, String onValue, String offValue) {
+        super(buttonId, x, y, width, height, buttonText, new String[] {onValue, offValue});
+    }
+
+    public boolean isOn() {
+        return getValue() == 0;
+    }
+}