fixed:
TmxImageLayer.h: In constructor 'Tmx::ImageLayer::ImageLayer(const Tmx::Map*)':
TmxImageLayer.h:93: error: 'Tmx::ImageLayer::image' will be initialized after
TmxImageLayer.h:89: error:   'float Tmx::ImageLayer::opacity'
TmxImageLayer.cpp:38: error:   when initialized here