mandatory anonymous section identifier

mandatory anonymous section identifier

This change makes sure there are no more anonymous (unnamed) sections
in configuration files. Previously it was optional and now the choice
is being removed.

All sections will have generated identifiers. This is important because
anonymous sections will be simpler to manipulate.

Signed-off-by: Antonio Paunovic <antonio.paunovic@sartura.hr>
Signed-off-by: Luka Perkov <luka.perkov@sartura.hr>