v1.81.1

• Removed lazy-created structs. This fixes the problem which addressed to situations, when Dear ImGui context dropped, but underlying pointer for structs didn't update;
• Added #isValidPtr()/#isNotValidPtr() to verify object uses the valid pointer;
• ImVec2/4 and type classes are now has #set(value) method, where value is another object of that class.
  Fox example: imFloat.set(new ImFloat()) or imVec2.set(new ImVec2());
• Added ImString#clear method to drop string content;
• Binding API now can return ImVec2/ImVec4 directly, without "dst" argument. Under the hood, such methods will create a new object and fill it with data;
• Added ImGuiStyle#getColors() to return float[ImGuiCol.COUNT][4] array with GUI colors;
• Fixed ImGui#getDragDropPayloadObject() threw exception if there were no payload.