(GitToolsGH-1932) Add Wyam Preview task

This will help with getting the docs setup, as it will allow viewing
the generated docs locally with live reload, to allow adjustments to be
made.

build.cake

@@ -37,6 +37,7 @@
 #load "./build/artifacts-test.cake"
 #load "./build/docker.cake"
 #load "./build/publish.cake"
+#load "./build/wyam.cake"
 
 using Xunit;
 using System.Diagnostics;

build/utils/paths.cake

@@ -25,6 +25,7 @@ public class BuildPaths
 
         var semVersion = version.SemVersion;
 
+        var sourceDir                     = (DirectoryPath)(context.Directory("./src"));
         var artifactsDir                  = (DirectoryPath)(context.Directory("./artifacts") + context.Directory("v" + semVersion));
         var artifactsBinDir               = artifactsDir.Combine("bin");
         var artifactsBinPortableDir       = artifactsBinDir.Combine("portable");
@@ -45,6 +46,7 @@ public class BuildPaths
 
         // Directories
         var buildDirectories = new BuildDirectories(
+            sourceDir,
             artifactsDir,
             nativeDir,
             buildArtifactDir,
@@ -93,6 +95,7 @@ public class BuildFiles
 
 public class BuildDirectories
 {
+    public DirectoryPath Source { get; private set; }
     public DirectoryPath Artifacts { get; private set; }
     public DirectoryPath Native { get; private set; }
     public DirectoryPath NugetRoot { get; private set; }
@@ -107,6 +110,7 @@ public class BuildDirectories
     public ICollection<DirectoryPath> ToClean { get; private set; }
 
     public BuildDirectories(
+        DirectoryPath sourceDir,
         DirectoryPath artifactsDir,
         DirectoryPath nativeDir,
         DirectoryPath buildArtifactDir,
@@ -120,6 +124,7 @@ public class BuildDirectories
         DirectoryPath artifactsBinFullFx472Dir
         )
     {
+        Source = sourceDir;
         Artifacts = artifactsDir;
         Native = nativeDir;
         BuildArtifact = buildArtifactDir;