Skinning engine changes

Overview of changes on Skinning engine for Kodi.

• Skinning engine v22
• Skinning engine v21
• Skinning engine v20
• Skinning engine v19
• Skinning engine v18
• Skinning engine v17
• Skinning engine v16
• Skinning engine v15
• Skinning engine v14
• Skinning engine v13
• Skinning engine v12