[librsvg] (12 commits) ...Merge branch 'alias-pixel' into 'master'

[Federico Mena Quintero <federico src gnome org>]

Summary of changes:

  a44c091... Add benchmarks for SharedImageSurface::from_pixbuf()
  3963938... No need to have extra long running time on these benchmarks
  01388f8... Add benchmarks for operations on surface_utils::Pixel
  5d00cb6... Define Pixel as an alias for rgb::RGBA8
  07aefc5... Use From trait implementations for conversion between Pixbu
  860ee01... Use rgb::ComponentMap to simplify test code
  64e8cef... Rewrite PixelOps::diff() using rgb::ComponentMap
  cd8a156... Use Pixel::map_rgb() to implement (un-)premultiplication
  4f9db85... Use integer math for Pixel::premultiply()
  1840469... Use 32 bit floating point for Pixel::unpremultiply()
  df05836... Move the check for fully transparent pixels into Pixel::unp
  78c3daa... Merge branch 'alias-pixel' into 'master'