load and save with new layers

[Casper Boemann]

With the autosizing layers the layers don't have size.

This gives problems when loading and saving our internal format.

I would like to know if we should make a backward compatible new file format 
or if it would be ok to just change the format.

more specifically the current fileformat stores some attributes of the layer 
including the size. then follows the data of the entire size.

With the new autolayers the data is grouped in tiles and there is no guarantee 
that all tiles exist. If I were to save in the current format I would then 
have to fill in all the non-tile areas with default data. That would make the 
file potentially large. Whats even worse is that when loading again all tiles 
would be created requiring much memory

I would like some form of tilebased fileformat where tiles can be omitted, 
just like in the new tilemanager.

best regards
Casper Boemann