Use existing installed python

1. use installed python
2. add settings to choose python directory
3. add py3 compability
4. create hello world python example

Wox.Core/UserSettings/PluginSettings.cs

@@ -1,16 +1,53 @@
 using System.Collections.Generic;
+using System.Linq;
+using Wox.Core.Plugin;
+using Wox.Plugin;
 
 namespace Wox.Core.UserSettings
 {
+    public class PluginsSettings
+    {
+        public string PythonDirectory { get; set; }
+        public Dictionary<string, Plugin> Plugins { get; set; } = new Dictionary<string, Plugin>();
 
-    public class PluginSettings
+        public void UpdatePluginSettings(List<PluginPair> plugins)
+        {
+            var metadatas = plugins.Select(p => p.Metadata);
+            foreach (var metadata in metadatas)
+            {
+                if (Plugins.ContainsKey(metadata.ID))
+                {
+                    var settings = Plugins[metadata.ID];
+                    if (settings.ActionKeywords?.Count > 0)
+                    {
+                        metadata.ActionKeywords = settings.ActionKeywords;
+                        metadata.ActionKeyword = settings.ActionKeywords[0];
+                    }
+                }
+                else
+                {
+                    Plugins[metadata.ID] = new Plugin
+                    {
+                        ID = metadata.ID,
+                        Name = metadata.Name,
+                        ActionKeywords = metadata.ActionKeywords,
+                        Disabled = false
+                    };
+                }
+            }
+        }
+
+        public void UpdateActionKeyword(PluginMetadata metadata)
+        {
+            var settings = Plugins[metadata.ID];
+            settings.ActionKeywords = metadata.ActionKeywords;
+        }
+    }
+    public class Plugin
     {
         public string ID { get; set; }
-
         public string Name { get; set; }
-
         public List<string> ActionKeywords { get; set; }
-
         public bool Disabled { get; set; }
     }
 }