storage fragmentation

[Dietmar Maurer <dietmar maurer-it com>]

Some file formats like the EFS or OLE2 format does not store the content

very compact. Instead there is unused space spread all over the file.

It is possible to compact the file doing a "save as" instead of a
"save".
I think MS leaves it up to the user to compact files, but his often
leads
to bloated files.

I suggest to implement a need_compaction() function for each driver.
If it return TRUE we can do a save_as in order to compact the file.

- Dietmar