Create command

[iamleeg]

We want to add to the command set of xcodeproj so that we can manipulate Xcode projects on non-Mac platforms. The first command is xcodeproj create PROJECT.

[igor-makarov]

@iamleeg Have you taken a look at Xcake? It's a fully featured project generator with an easy DSL that might already do what you need.

It uses Xcodeproj under the hood.

[iamleeg]

Thanks @igor-makarov, I hadn't! I have now, I'll check it out!

[iamleeg]

I've been using Xcake for the last month and it's sufficient for my needs. I leave it up to you whether you merge or reject this PR.