A simple method to force Unity Editor to recompile all scripts.

AssemblyUtility.cs

 public class AssemblyUtility
 {
  /// <summary>
  /// Forces Unity to recompile all scripts and then refresh. 
  /// </summary>
  public static void DirtyAllScripts()
  {
      // Grab the UnityEditor assembly
      Assembly editorAssembly = typeof(UnityEditor.Editor).Assembly;
      // Find the type that contains the method we want 
      Type compilationInterface = editorAssembly.GetType("UnityEditor.Scripting.ScriptCompilation.EditorCompilationInterface");
      // Make sure it's not null 
      if (compilationInterface != null)
      {
          // Create our binding flags
          BindingFlags staticBindingFlags = BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic;
          // Grab the dirty method 
          MethodInfo dirtyAllScriptsMethod = compilationInterface.GetMethod("DirtyAllScripts", staticBindingFlags);
          // Invoke the static method with no arguments.
          dirtyAllScriptsMethod.Invoke(null, null);
      }
      // Force the database to refresh.
      UnityEditor.AssetDatabase.Refresh();
  }
}