This change is being driven by:
- need for consistent terminology in the api. Currently there's
a confusing mix of border/outline used
- need for consistent terminology in the gui - we have a mix
of "border"/"outline"/"pen"
- bringing QGIS into line with the standard terminology used
in other graphic editing programs
Remove QgsAbstractProperty and subclasses, and instead use a single
QgsProperty class which covers the use of QgsAbstractProperty
and its subclasses. This simplifies the API and avoids pointer
handling. QgsProperty is implicitly shared for memory efficiency
and inexpensive copies.
Adds a new checkbox at the bottom of each symbol layer's
properties which allows you to control whether the layer is
enabled or not.
Disabled layers are not drawn, but are saved and can be
enabled at a later stage.
This makes it easier to tweak symbol appearance without
having to totally delete a symbol layer.
