Merge pull request #51 from morevnaproject/0.64.1

Fix Cygwin build environment
Fine-tune interpolation type icons and using all icnos in one sif file concept to enable easy maintainance
Delete unused sif interpolation type icon files
Cleanup by removing unused sif files according to the interpolation type icons update
Update canvas panel and import image layer icons

Since 0.64.0, we introduced a new icon for parameter of canvas, to have a consistant
icon metaphor, we update canvas and import image layer icons accordingly.
Add skeleton layer icon.
Add initial version of Stroboscope icon.
Correct the canvas panel icon
Use stroboscope and skeleton layer icons for layer tree
Add forbid animation icon(used in paramerter panel)
Make parameter list uses forbid animation icon instead of animate mod off icon

So that we can have consistant looking of icons for parameter panel.
Merge branch '0.64.1' into morevna

* 0.64.1:
  Make parameter list uses forbid animation icon instead of animate mod off icon
  Add forbid animation icon(used in paramerter panel)
  Use stroboscope and skeleton layer icons for layer tree
  Correct the canvas panel icon
  Add initial version of Stroboscope icon.
  Add skeleton layer icon.
  Update canvas panel and import image layer icons
  Cleanup by removing unused sif files according to the interpolation type icons update
  Delete unused sif interpolation type icon files
  Fine-tune interpolation type icons and using all icnos in one sif file concept to enable easy maintainance
temporary fix. in future we should to change type of return value of
method clone() to ValueNode::Handle