Add support for modifying a style.

Up to now it was only possible to modify the name, the description and
remove some iop from the style. It is now possible to add iop from
the selected image or to update it with the setting from the selected
image.
Minor code clean-up.
Use glong instead of long int for num in the gtk list store.

Indeed a G_TYPE_LONG corresponds to a glong which in turns corresponds
to a long int. But seems clearer to use glong as it emphasises the fact
that we are manipulating an item from a Gtk list store.
noise profile: require exact exif match

to distinguish '5D' and '5D Mark II'
First steps on a oAuth 2.0 Picasa module
Cleanup and rename picasa2 as picasa

  + Compile the module only if JSON is available
  + Keep the pwstorage as picasa2 to avoid clashes with already stored credentials from old module
Cleanup and addapt to the new dt_gui_key_accel_block_on_focus_* naming
Use separate section for iop from selected image in style dialog.

iop coming from the selected image are now in a separate section. This
is less confusing and makes the dialog cleaner.
Merge branch 'update-style'

* update-style:
  Use separate section for iop from selected image in style dialog.
  Use glong instead of long int for num in the gtk list store.
  Minor code clean-up.
  Add support for modifying a style.
Update fr.po
OpenBSD 5.3 has dprintf
colorspaces: workaround horrible brokenness of some printshops
rawspeed: support Panasonic DMC-LX7 16:9 and 1:1 aspect ratio modes
usermanual: a few further changes to chapter 1
CR : add new string for translators
Cleanup debug code, and embrace some other around a #ifdef block
ellipsize the text in comboboxes to avoid them to grew beyond the panel size
Merge remote-tracking branch 'upstream/master'
Fix style
Add defensive code to avoid assertions violation reported on the console.