[librsvg] (10 commits) Created branch drawing-ctx-wip

[Federico Mena Quintero <federico src gnome org>]

The branch 'drawing-ctx-wip' was created.

Summary of new commits:

  0ccc1d8... wip: try to port drawing_ctx to rust
  b054df6... bbox: remove the C export
  603b29f... drawing_ctx: pass the context to the draw callback
  3156161... Clone the draw_ctx's bbox so the ctx doesn't get borrowed
  10f5167... Compute effects region in a way to not cause a double mutab
  ffc59ce... Store RsvgNode in draw_ctx.acquired_nodes, not pointers to 
  8b37a31... Use a RefCell for the vector of acquired nodes
  6287274... Clone a bbox to avoid causing a borrow
  ffabcab... DrawCtx is always mutable in the filter context
  90b3682... DrawingCtx.get_cr_stack() doesn't need a mutable ctx