add get_binding_text() for script api

doc/en/scripting/user-input.md

@@ -60,6 +60,12 @@ input.get_bindings() -> strings array
 
 Returns all binding names.
 
+```python
+input.get_binding_text(bindname: str) -> str
+```
+
+Returns text representation of button by binding name.
+
 ```python
 input.is_pressed(code: str) -> bool
 ```

doc/ru/scripting/user-input.md

@@ -58,6 +58,12 @@ input.get_bindings() -> массив строк
 
 Возвращает названия всех доступных привязок.
 
+```python
+input.get_binding_text(bindname: str) -> str
+```
+
+Возвращает текстовое представление кнопки по имени привязки.
+
 ```python
 input.is_active(bindname: str) -> bool
 ```

src/logic/scripting/lua/libs/libinput.cpp

@@ -64,6 +64,20 @@ static int l_get_bindings(lua::State* L) {
     return 1;
 }
 
+static int l_get_binding_text(lua::State* L) {
+    auto bindname = lua::require_string(L, 1);
+    auto index = Events::bindings.find(bindname);
+    
+    if (index == Events::bindings.end()) {
+        throw std::runtime_error("unknown binding " + util::quote(bindname));
+        lua::pushstring(L, "");
+    } else {
+        lua::pushstring(L, index->second.text());
+    }
+
+    return 1;
+}
+
 static int l_is_active(lua::State* L) {
     auto bindname = lua::require_string(L, 1);
     const auto& bind = Events::bindings.find(bindname);
@@ -101,6 +115,7 @@ const luaL_Reg inputlib[] = {
     {"add_callback", lua::wrap<l_add_callback>},
     {"get_mouse_pos", lua::wrap<l_get_mouse_pos>},
     {"get_bindings", lua::wrap<l_get_bindings>},
+    {"get_binding_text", lua::wrap<l_get_binding_text>},
     {"is_active", lua::wrap<l_is_active>},
     {"is_pressed", lua::wrap<l_is_pressed>},
     {NULL, NULL}};