Allow OldestMatching resolution strategy about paket

[forki]

/cc @agross

[agross]

If this flag is to make the transition easier with packages that rely on nuget's broken dependency resolution, it needs to apply to all the direct and indirect dependencies of the nuget as well.

I think there will be a time going forward where we see lots of packages with broken dependency constraints. Castle.Windsor, for example, relies on nuget's resolver to install the lowest matching Castle.Core. With Paket's semver resolution it will get latest, thus breaking the build (because of strong-named assemblies, oh joy!).

Does F# provide other means to define the flag? New named parameter? What are our options?

[forki]

How about

nuget-compatible "FSharp.Formatting" "~> 2.2" 
nuget-oldest "FSharp.Formatting" "~> 2.2"

For optional parameters we need parentheses.

[agross]

Looks fine!

[agross]

nuget "Castle.Windsor" "!= 3.2" 
// or
nuget "Castle.Windsor" "== 3.2"

// Look for 3.2 <= x < 4, but use nuget-style resolution for its dependencies
nuget "Castle.Windsor" "!~> 3.2"

[forki]

We still need to document this.