tar plugin

A source implementation for staging tar files

Usage:

# Specify the tar source kind
kind: tar

# Specify the tar url. Using an alias defined in your project
# configuration is encouraged. 'bst track' will update the
# sha256sum in 'ref' to the downloaded file's sha256sum.
url: upstream:foo.tar

# Specify the ref. It's a sha256sum of the file you download.
ref: 6c9f6f68a131ec6381da82f2bff978083ed7f4f7991d931bfa767b7965ebc94b

# Specify a glob pattern to indicate the base directory to extract
# from the tarball. The first matching directory will be used.
#
# Note that this is '*' by default since most standard release
# tarballs contain a self named subdirectory at the root which
# contains the files one normally wants to extract to build.
#
# To extract the root of the tarball directly, this can be set
# to an empty string.
base-dir: '*'