Version 2.44.0
- Librsvg now has minimal logging for debugging by setting the
  RSVG_LOG environment variable.  See CONTRIBUTING.md for details.
- Speed improvements for Gaussian blur, SRGB conversions, and various
  filters (Ivan Molodetskikh).
- Fix #264 - the letter-spacing property now supports "normal" in
  addition to lengths (Paolo Borelli).
- Fix #318 - the font-weight property was being parsed incorrectly.
- Fix #323 - don't use 100% "forever" with malicious SVGs that cause
  an exponential number of elements to be instanced through the
  <use> element.  We limit the number of <use> instances now.
- Fix #293 - Don't panic when masking an empty group.
- Fix #319 - Parse single font-family correctly.
- Cleanups for the internal representation of elliptical arcs in paths
  (letheed).