hexcurse exit after failed save&exit

[errge]

When I try to edit a read-only file on the filesystem and choose exit, hexcurse asks me if I want to save it first. So far so good, but when I choose yes, it tells me "bad permission" and then exits. Therefore I lose all my current changes. Instead, it should continue running, so I can handle the issue. Either by getting permissions in an another terminal window or saving as a different filename.

[ghost]

Closing out as this was already merged into master.