Bug 801: Elaborate on multisampling performance/quality: Flipquad, RGSS, Quincunx

Using poles only as sampling points is not as effective as: flipquad > rgss >> quincunx

Best quality would be 'wholeedge', i.e. average every supersample,
however performance is worse here.

References:
  <http://fileadmin.cs.lth.se/graphics/research/papers/inexp_ms2005/>
  <http://fileadmin.cs.lth.se/graphics/research/papers/masses2003/>
ShaderCode: Allow 'srcRoot' to be optional ; RegionRendererImpl01: Allos custom shader