message: honour PYTHONHOME in build procedure
diff: using UnrealBuildTool;
  using System.IO;
  +using System.Collections.Generic;
  public class UnrealEnginePython : ModuleRules
  {
  @@ -157,7 +158,13 @@ public class UnrealEnginePython : ModuleRules
  private string DiscoverPythonPath(string[] knownPaths)
  {
  - foreach (string path in knownPaths)
  + // insert the PYTHONHOME content as the first known path
  + List<string> paths = new List<string>(knownPaths);
  + string environmentPath = System.Environment.GetEnvironmentVariable("PYTHONHOME");
  + if (!string.IsNullOrEmpty(environmentPath))
  + paths.Insert(0, environmentPath);
  +
  + foreach (string path in paths)
  {
  string headerFile = Path.Combine(path, "include", "Python.h");
  if (File.Exists(headerFile))
  