[librsvg] (26 commits) ...(#237): Use cssparser and selectors, not libcroco

[Federico Mena Quintero <federico src gnome org>]

Summary of changes:

  887fb8a... element_name() - return a QualName, not a str
  4406568... Temporary snapshot of various servo crates
  8ced490... Depend on the selectors crate
  2c47d30... NodeChars::is_empty() - new method
  eb86c9f... Start defining the types that SelectorImpl requires
  8d3c6f4... Use the same cssparser version that Servo requires
  ef8da41... First implementation of selectors::Element
  f42d533... derive_common: Fix example in documentation
  2b251eb... Rename function to append_stylesheet_from_xml_processing_in
  6f7e6b8... Load the stylesheet directly in append_stylesheet_from_xml_
  02be814... Add a state for parsing <style> to XmlState
  8928168... Store the stylesheet data in the Style node and load it whe
  5d4e309... Rename CssRules to Stylesheet
  6e10007... DocumentBuilder: store a list of stylesheets, not a single 
  04e27e5... Implement selectors::Parser and cssparser::QualifiedRulePar
  644da96... Implement cssparser::QualifiedRuleParser and do matching wi
  03ce9bd... Remove references to libcroco
  c2cb0d5... Internals documentation for the css module
  4aeef8c... Rename property names to prop_name in general
  579f69f... Implement minimal handling of @import
  285e005... Cover both variants of @import
  cb62442... document: remove uneeded map_err
  7273e97... css: make code shorter and idiomatic
  014c290... css: simplify code
  2258fdf... css: rename RsvgSelectors to Selector
  cad0967... (#237): Use cssparser and selectors, not libcroco