removed todos and empty lines in Block.hpp

Signed-off-by: Jan Grewe <jan.grewe@g-node.org>
removed todo and minor cleanup in Property.hpp

Signed-off-by: Jan Grewe <jan.grewe@g-node.org>
docstrings for dimension methods

Signed-off-by: Jan Grewe <jan.grewe@g-node.org>
refactoring of user interface classes.
monster commit due to catastrophic rebase :-(
resolved conflicts in EntityWithSources