fixed bug in Charon<string>::readAttr and wrtieAttr... dirty hack,
somehow
Block has a block_id, respective getter and setter methods, deleting of Blocks by Block ...
BlockIterator: some changes
Util: function for id generation in separate namespace pandora::util.
BaseContainer: refactoring from BaseContainer to Group.
File, Block: now use Group instead of extending BaseContainer.
pandora.hpp: updated documentation.
pandora.hpp: updated copyright notice
Util: updated documentation
File: update documentation.
Merge branch 'group'
Merge branch 'stoewer-dev'
Iterator: implementation of group and block iterator (untested)
Iterator: fixed compiler errors and warnings
Iterator: headers and imports
BlockIterator: working version
Merge branch 'master' into stoewer-dev