Cleaned up the reflection code a bit

* Renamed 'tag' variable to 'handler'
* Removed addAlias stuff, instead check for matching names with if statements
* Added after_reading function that is called by Reader after reading a complete object. This generalizes Packaged::validate, which is now also called via this mechanism.
* Removed some backwards compatibility with <0.3.0 for templates

src/data/field/choice.hpp

@@ -42,6 +42,7 @@ class ChoiceField : public Field {
   map<String,Color> choice_colors_cardlist;  ///< Colors for the various choices, for in the card list
   
   virtual void initDependencies(Context&, const Dependency&) const;
+  virtual void after_reading(Version ver);
 };