Add support for metadata from non-TOC/Lua files

[Predicate]

Ideally, AddonDoc should be able to present all available metadata about an addon, including information found in files not read by the WoW client itself. Useful features would include:

• .pkgmeta parsing
  • Ignore paths specified in ignore
  • Create pseudo-addons for documentation based on move-folders
  • Fill in true dependencies for addons with "embedded" setups, using required-dependencies and optional-dependencies
• .docmeta parsing
  • Link to documentation hosted on other sites instead of generating docs (optional)
  • Skip documentation for formats not supported by AddonDoc
  • Follow output-page and output-directory directives
• LICENSE detection; attempt to display the appropriate license for each addon
• Inclusion of other unrecognized files, e.g. for README, changelogs, etc.