When generating the manual node (/dir), we need to ensure that the
default-directory is set to the package root, otherwise the file is
ignored in some other repository, that probably doesn't exist.
* package.el (package--parse-elpaignore): Add new function.
(package--compile): Bind 'byte-compile-ignore-files' to the result of
'package--parse-elpaignore'.
* package-vc.el (package-vc-probable-repository-regexp): Add new user option.
(package-vc-sourced-packages-list): Add new function using
'package-vc-probable-repository-regexp'.
(package-vc-fetch): Use 'package-vc-sourced-packages-list'.
Note that the "package kind" was renamed from "source" to "vc".
* package-vc.el: (package-vc-commit): Copy from package.el
(package-vc-version): Add new function
(package-vc-generate-description-file): Add new function.
(package-vc-unpack): Add new function.
(package-vc-fetch): Copy from package.el
(package-checkout): Add alias for package-vc-fetch
* package.el (package-devel-dir): Remove option. The checkouts are
stored in package-user-dir
(package-desc): Handle (vc . VERS) version strings
(package-desc-full-name): Return the plain name for vc packages
(package-devel-commit): Move function to package-vc
(package-load-descriptor): Refactor according to other changes
(package-load-all-descriptors): Remove package-devel-dir
(package-unpack): Remove vc package handling
(package-generate-description-file): Remove special handling for vc
packages
(package-install-from-archive): Remove special handling for vc
packages
(package-fetch): Move function to package-vc
(package-desc-status): Use "vc" instead of "source"
(package--remove-hidden): Use "vc" instead of "source"
(package-menu--print-info-simple): Refactor according to other changes
