v0.6.0

Changed

• Delete the ability to explicitly specify multiple files, and have the effect
  of one file being specified be the same as the former --dir-mode. See
  #16 for more details.
• Delete protoc_include_wkt setting. This is always set to true.
• Delete no_default_excludes setting. This is always set to true.
• Delete gen.go_options.no_default_modifiers setting.
• Delete lint.group setting.
• Delete harbormaster global flag.
• Refactor create.dir_to_base_package to the list create.packages See
  the documentation for more details.
• Rename create.dir_to_base_package -> create.dir_to_package.
• Move prototool init to prototool config init.
• Move gen.plugin_overrides to gen.plugins.path.
• Refactor lint configuration. See the documentation for details.
• Refactor format --no-rewrite so that the previous default is now enabled via
  format --fix.

Fixed

• Fix excludes setting to correctly match file path prefixes.