Originally, ld_lua_load_file_to_category() was adding
registered symbols into a passed LdSymbolCategory object.
This interface has been rewritten to be more generic
by using callbacks to notify about new symbols.
The previous method of containment, that is using GHashTable,
did not list children in any particular order.
Also names of children were duplicated. One copy has been
stored as a hash table index and another was present in the
child itself.
This step is needed, since the current design is quite chaotic
and it would not be possible to finish the application.
There's still a lot to be done.
After this step, it's time to implement the rest of LdLua.
