Deprecation warnings unhidden

[Stephen Kennedy <stevek gnome org>]

Hi all, FYI I've disabled a very old bit of code which hid deprecation warnings.
I think the reason they were hidden in the first place has gone away
(pygtk 2.6 support)
I've also refactored code to remove the most obvious warnings (mostly replacing
popen variants with subprocess).

I don't get any warnings locally for the most common operations but I'd like to
hear if anybody else sees some new ones.

Stephen.

http://git.gnome.org/cgit/meld/commit/?id=acef43d5151789cfa8e0b3226ad333956ab66a6d
http://git.gnome.org/cgit/meld/commit/?id=63b268abd3c709a4cb88699af5b0489300fc0279