frame dialog HIG love

Hello,

the attached patch gives some HIG love to the "format frame" dialog.

Namely:
- Remove extra labels for checkboxes and radio buttons
- Make window resizable
- Proposal for background: "Select Image" and "Set no Image" buttons
using stock icons

I also fixed some of the more obvious gtk runtime errors that were
spewn out when the dialog was opened.
AFAICT this also fixes
http://bugzilla.abisource.com/show_bug.cgi?id=7374

Seems like the checkbox for text wrapping is not i18n-ized, will do
if you tell me how.

Please tell me what you think about it.
Rob