rem: surface.populate();
add: shadeTest<Mercator::FillShader>(segment); shadeTest<Mercator::HighShader>(segment); shadeTest<Mercator::LowShader>(segment); shadeTest<Mercator::BandShader>(segment);
context: int main(){    Mercator::Segment segment;    Mercator::FillShader fill_shader;    Mercator::Surface surface(segment, fill_shader);    surface.populate();}