Added Package.swift for Swift Package Manager support

[mluisbrown]

Tested using swift build from the latest development drop of Swift.

[dmcrodrigues]

Build ✅

✨

[dmcrodrigues]

Closes #46.

[RuiAAPeres]

Not sure if this is still up to date but:

You will need to make sure your .Swift files are in a Sources folder.

All the packages here follow that.

[dmcrodrigues]

I'm not sure if that is still required.

It is acceptable to have no Sources directory, in which case the root directory is treated as a single module (place your sources there) or sub directories of the root are considered modules.
Reference: Source Layouts

Maybe we should run some tests to be sure.

[RuiAAPeres]

I think we should go with Source to be sure:

(...)or sub directories of the root are considered modules.

In our case it would work.

[mluisbrown]

I tested it with the layout we have now and it works. swift build in the root creates .build/debug/Vinyl.swiftmodule. .swiftmodule files can be imported into other projects. I had to add an exclude section in Package.swift so that VinylTests and Carthage folders are ignored.

[RuiAAPeres]

@mluisbrown y good job.

[mluisbrown]

Also, see this thread on swift-users mailing list. Confirms that .swiftmodule output is all you need to import module into a client package.