If multiple threads call a function with a static function
simultaneously for the first time, C++ does not guarantee that the
static member will be constructed correctly. Make sure that it happens
correctly.
Creating all the presets as vtkm::cont::ColorTable objects and passing
them back was problematic. It caused state to be shared and caused
issues when deallocating after the device deallocation methods were
finalized. Instead, make a simple struct and build new color tables on
the fly.
