Particles: Add option to render without point levels

Usually point sprites, when available, are faster and require less memory than triangle particles. But on some systems it might be preferred to not use points, maybe because driver bug, rendering quality, performance etc. So consider adding either a direct property or more general "renderingHints" property which can be used to set perf level always at least Colored. (Currently Colored is used only on d3d11, other backends use SimplePoint/ColoredPoint and jump over Colored to Deformable.)