[API] Added callback binding for InputText (#156)

* Added callback binding for InputText

* Add JavaDoc

* Change

* Add Javadoc

* Fix Import

* Teaks and improvements

- Extended example;
- Added input text callback ImGuiInputTextFlags#CallbackEdit;
- Minor code improvements.

---------

Co-authored-by: SpaiR <klimbetoo@gmail.com>

imgui-binding/src/main/java/imgui/callback/ImGuiInputTextCallback.java

@@ -0,0 +1,17 @@
+package imgui.callback;
+
+import imgui.ImGuiInputTextCallbackData;
+
+import java.util.function.Consumer;
+
+/**
+ * Callback to use in {@link imgui.ImGui#inputText(String, imgui.type.ImString, int, ImGuiInputTextCallback)}.
+ */
+public abstract class ImGuiInputTextCallback implements Consumer<ImGuiInputTextCallbackData> {
+    /**
+     * This function will be called by the native Callback and wrapped.
+     */
+    public final void accept(final long ptr) {
+        accept(new ImGuiInputTextCallbackData(ptr));
+    }
+}