libsmartcols: make indexing more flexible

Signed-off-by: Ondrej Oprala <ooprala@redhat.com>
libsmartcols: only use scols_table_add_column() internally

Signed-off-by: Ondrej Oprala <ooprala@redhat.com>
libsmartcols: clone cell structs properly

Signed-off-by: Ondrej Oprala <ooprala@redhat.com>
libsmartcols: add basic cell API

Signed-off-by: Ondrej Oprala <ooprala@redhat.com>
libsmartcols: sort and clean up libsmartcols.sym

Signed-off-by: Ondrej Oprala <ooprala@redhat.com>
libsmartcols: add reference counting

Signed-off-by: Ondrej Oprala <ooprala@redhat.com>