Slightly optimised code style and add more functionality

- optimised UI
- check conflicts when change key bind if the key has already been in use
- abstract keybind as a separate singleton class so all class can access it
- [WIP] turning mode is need to be finished

#story[1245]

src/main/resources/css/dialogs/KeyBindingDialog.css

@@ -1,40 +1,32 @@
 #keyBindingDialogHeader {
-    -fx-font-size: 30px;
+    -fx-font-size: 27px;
     -fx-text-fill: -fx-pp-dark-text-color;
 }
 
 JFXButton {
     -fx-background-color: -fx-pp-light-text-color;
     -fx-text-fill: -fx-pp-theme-color;
-    -fx-font-size: 15px;
-    -fx-effect: -fx-pp-dropshadow-light;
+    -fx-font-size: 13px;
 }
 
 Label {
-    -fx-font-size: 20px;
+    -fx-font-size: 15px;
     -fx-text-fill: -fx-pp-theme-color;
     -fx-effect: -fx-pp-dropshadow-light;
 }
 
-JFXButton:hover {
-    -fx-font-size: 18px;
-    -fx-background-color: -fx-pp-light-theme-color;
-    -fx-text-fill: -fx-pp-light-text-color;
-}
-
-JFXButton:focused {
-    -fx-font-size: 18px;
-    -fx-background-color: -fx-pp-theme-color;
-    -fx-text-fill: -fx-pp-light-text-color;
-}
-
 JFXToggleButton {
     -jfx-toggle-color: -fx-pp-theme-color;
     -fx-text-fill: -fx-pp-theme-color;
 }
 
-#resetBtn, #confirmBtn {
+#resetBtn {
     -fx-background-color: -fx-pp-theme-color;
     -fx-text-fill: -fx-pp-front-color;
     -fx-effect: -fx-pp-dropshadow-light;
+    -fx-font-size: 18;
+}
+
+#resetBtn:hover {
+    -fx-font-size: 20;
 }