* use own default constructor error: default initialization of an object of const type 'const BlackMisc::CIcon' without a user-provided default constructor static const CIcon empty;
* same for CDbOwnModelsComponent()
* fixed guard
This also means moving Mixin::Icon from CContainerBase one step down the inheritance hierarchy
to resolve what would otherwise have been a circular include dependency.
The following issues were fixed
* Fixed wrong/missing namespaces
* Fixed obvious typos in documentation
* Documentation not in sync with source code
refs #544
* DBus mixins moved to dbus.h
* Json mixins moved to json.h
* Icon mixin moved to icon.h
* Comparison mixins moved to compare.h
* Hash and string mixins moved to blackmiscfreefunctions.h
* Index mixin moved to propertyindexvariantmap.h
* MetaType mixins moved to variant.h
* registerMetaValueType moved to variant.h
* valueobject_private.h renamed to variant_private.h
* Involves rearranging some header includes to break cyclic include dependencies,
* Adding a new, simple base class CEmpty,
* Removing any remaining polymorphic uses of CValueObject with templates,
* Adding a new trait for use with enable_if to restrict templates to work only with value objects,
* Replacing the polymorphic/runtime multimethod-based compare functions with static/compile-time compare functions.
* Moved methods to cpp file (less recompilation)
* Background of icons can be changed
* refs #322, changed to index based approach for retrieving icons (faster)
* therfore: sorted icons per name, easier to keep in sync
* renamed fromQVariant to convertFromQVariant, the "from" methods imply the object is changed (fromJson, fromString ..)
* implemented fromQVariant - changing the object by QVariant
* moved toQVariant into PQ template
* free function setFromQVariant
