* canvas bitmaps created without transparency get an appropriate color
  space
* implement a color space for OpenGL RGBA to use instead of
  canvas::tools::getStdColorSpace(), which apparently uses VCL's
  interpretation of alpha (alpha == 0xff means full transparency,
  alpha == 0 full opacity).

Change-Id: I97f30533206b75132abd0bb0d290a279f15ae8a9