v0.3.0

Fixed

• Fix a bug that prevented existing headers from being found
  if they followed a document prologue.

Changed

• Standardize how configurations for styles, prologues, and templates are found.

  This helps ensure that the most specific configuration for a given file is always used.
  For example, code interacting with a file with two extensions (like .jinja.html)
  will consistently find a configuration for .jinja.html before .html.

• Rename prolog to prologue everywhere.

• Rename the configuration keys style and prolog to styles and prologues.

• Eliminate the "default" config key.

Development

• Add a workflow that tests Chipshot using GitHub actions.