[librsvg] (22 commits) ...Merge branch 'refactor-pattern'

[Federico Mena Quintero <federico src gnome org>]

Summary of changes:

  f2ca1bb... pattern: set the weak ref on the result, not the long-lived
  52a4ecd... Use a strong reference to the pattern's node that has the c
  aef62b0... Comment out RsvgWeakNode; it is unused
  2a9a56c... NodePattern: move the fallback field to the end
  8b0d6f9... gradient: really make resolve_from_defaults() immutable
  4c07bff... Make resolve_from_*() take &self, not &mut self
  f8f2f55... Prepare trait Resolve for immutability later
  9f4ef22... NodePattern: make fields private
  fe8915f... NodePattern: move common fields to a Common struct
  0f34a58... pattern: split off an UnresolvedPattern, similar to the gra
  41e5c9d... NodePattern: cache the resolved Pattern
  a3043ae... Introduce UnresolvedNodeWithChildren to finally keep track 
  96cdcf5... Rename to UnresolvedChildren / Children
  5da875a... Rename PaintServerError to AcquireError
  8a90d6c... Make get_node_from_type() return a Result, not an Option
  abb4e68... Make get_node() return a Result, not an Option
  878b08e... Make get_node_of_type() take a slice of valid types, instea
  3b0da95... Remove the public AcquiredNodes::get_type(); use get_node_o
  2421bab... Rename get_node_of_type() to just acquire()
  78670b2... Make AcquiredNodes private; use DrawingCtx::acquire_node() 
  2321911... Rename trait and method to AsPaintSource::set_as_paint_sour
  f8c907f... Merge branch 'refactor-pattern'