lua: textbox.text, placeholder properties

src/frontend/gui/controls.cpp

@@ -361,10 +361,18 @@ std::wstring TextBox::getText() const {
     return input;
 }
 
-void TextBox::setText(std::wstring value) {
+void TextBox::setText(const std::wstring value) {
     this->input = value;
 }
 
+std::wstring TextBox::getPlaceholder() const {
+    return placeholder;
+}
+
+void TextBox::setPlaceholder(const std::wstring& placeholder) {
+    this->placeholder = placeholder;
+}
+
 // ============================== InputBindBox ================================
 InputBindBox::InputBindBox(Binding& binding, glm::vec4 padding) 
     : Panel(glm::vec2(100,32), padding, 0),