Sycles addon 2.1.2

What's new:

• Add Premultiply Alpha parameter to the Cycles image shader node. Also use the parameter Enable Copy Alpha to RGB as similar parameter in the default image shader node.
  
• Fix bug with image clip shader node connected to the compound input port
• Fix bug with wrong color of the instances after scene update
• Support visibility parameter, which allows to hide/unhide master object of instances
  
• Some other small improvements