* BLOCK_SELECTOR class is not longer derived from EDA_ITEM.
* Encapsulate BLOCK_SELECTOR class member variables and add access methods.
* Move HandleBlockBegin() function from block_commande.cpp to drawframe.cpp.
* Remove virtual methods from top level derived objects per future
  coding policy change.
* Remove Doxygen copydoc statement from objects derived from EDA_ITEM
  since the comments are automatically copied to the derived object.
* Removed copy and pasted Doxygen comments from objects derived from
  EDA_ITEM.