New action LayerAutlineRegion, which creates new outline layer. Not
creates vertices link. No GUI entry.
Register OutlineRegion action common actions list (make visible in GUI)
Test implementation of outline region action - creates blank outline.
OutlineRegion action now creates valid outline with default witdh
Extract applying default param values from method
CanvasInterface::add_layer_to() into separate method
CanvasInterface::apply_layer_param_defaults(). So default parameters can
be applied for already created layers.
OutlineRegion action now creates outline with current color, width etc
OutlineRegion action: fix depth of new outline
Hide OutlineRegion action when it not applicable for selected layer
Renamed layeroutlineregion.h to layermakebline.h, and
layeroutlineregion.cpp to layermakebline.cpp
Rename
New actions instead "outline region": "Make Outline", "Make Advanced
Outline", "Make Region". All of these available for layers with "bline"
("Vertices") parameter.
Improve Action::LayerMakeBline.

Types of possioble "base" layers configured individually for "make
outline", "make advanced outline" and "make region" actions. So "make
outline" available for advanced outlines and regions, "make advanced
outline" for outline and regions etc...

New regions creates behind selected layer.
Merge pull request #27 from blackwarthog/contour-tools

Contour tools
Store "radius" parameter of Circle layer as ValueBase.
A few TODO notes
Store "angle" parameter of Star layer as ValueBase.
Update UnSetStatic action too.
Reorganize save routines for static option
Add interpolation option for ValueBase. Implement loading and saving for it.
Reorganize code. Now interpolation option isn't lost when parameter is changed.