Add new type of ValueDesc - sub-value. Also rename method
'parent_is_layer_param' to 'parent_is_layer'
hasher from GUID
Improve guid for ValueDesc
Fix ValueDesc::get_value
Improve sub-ValueDesc
Change duckmatic to use sub-valuedesc
Link tangents and widths to spline
Fix bug with linked vertices
Fix tangent editing
Track spline tangents linked to other spline
Split tangents when link to spline
Track transforamation linked to spline
Fix tangents handles
Fix behavior of star (and others) linked to spline
Fix group transparency
Fix crash for Magick++, Gif and other targets utilizing init() function