Swift Package Manager 4 support

[rootscript]

Would be great if this could work with SPM4, so that is could be used like so in Package.swift:

// swift-tools-version:4.0

import PackageDescription

let package = Package(
    name: "Test01",
    dependencies: [
        .package(url: "https://github.com/nomothetis/OptionKit.git", from: "1.0.0"),
    ],
    targets: [
        .target(
            name: "Test01",
            dependencies: ["OptionKit"]),
    ]
)

Currently running swift package generate-xcodeproj returns:

error: noManifest(baseURL: "https://github.com/nomothetis/OptionKit.git", version: Optional("1.0.0"))
error: product dependency 'OptionKit' not found

[rootscript]

Here's a link, which i believe helps:

Updating an Existing Package to the Swift 4 Manifest Format

https://swift.org/blog/swift-package-manager-manifest-api-redesign/