update gradle project, parallel for-loop based on std::thread on android, fix mipmaps on TextureManager

src/node_panel_brush.cpp

@@ -196,6 +196,7 @@ void NodePanelBrushPreset::init()
         //brush->m_brush->m_tip_size = .05f;
         brush->m_preview->m_brush = brush->m_brush;
         brush->m_preview->draw_stroke();
+        brush->m_thumb->m_use_mipmaps = true;
         brush->m_thumb->set_image(brush->m_brush->m_brush_thumb_path);
         brush->on_click = std::bind(&NodePanelBrushPreset::handle_click, this, std::placeholders::_1);
         save();