[AD] Relative paths in the grabber

[Evert Glebbeek <eglebbk@xxxxxxxxxx>]

I've made a preliminary patch (roughly 9kb) that adds the ability to store 
relative paths in the orig property. I've tested it using the grab option 
in the grabber and it works quite well, but not for things like grab from 
grid and update (yet).
Now I have a few questions (and some fine-tuning to do) before submitting 
a final patch:

1) It adds another checkbox to the grabber window, which really doesn't 
fit. I'd imagine there's also a new checkbox for the sort patch posted by 
Vincent. What will be the policy for these checkboxes? I squeezed mine in, 
but it's *very* ugly and breaks in higher resolutions. Will there be a 
datafile-properties popup-menu instead of the boxes in the main window?
Any thoughts on this?

2) It's currently a hack in the function that handles the grab command. 
I'd like this to work for update and grab-from-grid as well, but as far as 
I can see, this requires some heavy modifications to datedit.c. How 
serious would breaking backward compatibility for datedit be?

3) Currently, when the option is active it applies to new entries, but 
doesn't touch existing ones. Is it desireable to change this? I'm guessing 
no, but thought I'd ask anyway.

Evert