Add convenience extensions to TextTransformationExtensions

[gitfool]

I would like to add convenience extensions to TextTransformationExtension:

Support for dictionaries:

public static TextTransformation<TTemplate> WithTokens<TTemplate>(
    this TextTransformation<TTemplate> transformation, IDictionary<string, object> tokens)
    where TTemplate : class, ITextTransformationTemplate
{
    if (transformation != null && tokens != null)
    {
        foreach (var token in tokens)
        {
            if (token.Value != null) // leave placeholder for tokens without a value
            {
                transformation.Template.Register(token.Key, token.Value);
            }
        }
    }
    return transformation;
}

Support for shallow object properties, with optional key prefix, that feeds the first extension method:

public static Dictionary<string, object> ToTokens(this object value, string prefix = null, BindingFlags? bindingAttr = null)
{
    return value?.GetType()
        .GetProperties(bindingAttr ?? BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public)
        .ToDictionary(property => string.Concat(prefix, property.Name), property => property.GetValue(value));
}

Thoughts? Happy to submit a PR!

[gitfool]

Here's an example of how to use the ToTokens convenience extension:

Task("StageManifest")
    .Does(() =>
{
    TransformTextFile(Build.Files.Manifest, "{{", "}}")
        .WithTokens(Build.Version.ToTokens("Version."))
        .Save(Build.Files.ArtifactsManifest);
});

where the manifest contains placeholders for Version properties (of type GitVersion):

---
name: Test
version:
    semantic_version: {{ Version.FullSemVer }}
    assembly_version: {{ Version.AssemblySemVer }}
    assembly_file_version: {{ Version.AssemblySemFileVer }}
    informational_version: {{ Version.InformationalVersion }}
...

[gitfool]

I use a much more elaborate ToTokens extension now... Cake.Dungeon/scripts/extensions.cake#L9.