Support for XPkg packages.
Usage:
import XPkgPackage
let links = [
["local/file", "~/place/to/link/file"],
]
let package = InstalledPackage(fromCommandLine: CommandLine.arguments)
try! package.performAction(fromCommandLine: CommandLine.arguments, links: links)Provides a way to parse the arguments passed by xpkg, and get back a struct representing this package.
The struct supplies an API for creating links, running commands, and finding out which xpkg action is being performed.