Patch: don't save tiles that are equal to the default tile

[Boudewijn Rempt]

On Tue, 16 Mar 2010, Dmitry Kazakov wrote:

> I don't think we need this.
> 
> KisTileHashTableIterator returns the number of non-default tiles, or (more
> precisely) the number of preallocated tiles. After you fixed the extents
> bug, these terms coincide. So this check is superfluous.

Isn't it so that within a rectangle of allocated tiles there can be
unallocated, default pixel, tiles?

> 
> There is (was?) another bug you can fix: after loading a .kra file the
> default pixel of the paint device is not restored and is set to (0,0,0,0). I
> think this should be done at the level of KisPaintDevice.

I