[librsvg] (15 commits) ...Merge branch 'float-comparison'

[Federico Mena Quintero <federico src gnome org>]

Summary of changes:

  2551641... Depend on float-cmp so we can get traits for approximate co
  91b698e... New trait FixedEqCairo with a fixed_eq_cairo() method
  d2f85cb... New trait ApproxEqCairo
  0c756a3... path_builder.rs: Use approx_eq_cairo() instead of direct fl
  9b0dc7a... pattern.rs: Tighten division-by-zero guards; use approx_eq_
  125bb9f... util.rs: Make DBL_EPSILON private; we'll remove it soon
  3a8b553... RsvgBbox: use approx_eq_cairo() instead of double_equals()
  68275e1... marker.rs: Use approx_eq_cairo() and float_cmp::ApproxEq in
  bed4fb0... structure.rs: Use approx_eq_cairo() instead of double_equal
  0c8554b... viewport.rs: Use approx_eq_cairo() instead of double_equals
  28a457b... util.rs: Remove DBL_EPSILON and double_equals().  Yay!
  647cfcc... Use ApproxEq again in ApproxEqCairo.  This lets us compare 
  6e5356f... CONTRIBUTING.md: Link to ARCHITECTURE.md
  3431a1b... ARCHITECTURE.md: Document how to compare floating-point num
  dd8a120... Merge branch 'float-comparison'