Add rawappend, catch Throwable, ignore temp files

- Added .rawappend extension which instructs the manager to append the
file using pre-1.2 appending mode
- Catching a Throwable instead of an Exception allows the manager to
gracefully recover from an OutOfMemoryError... But too general a catch
case = bad?
- Told the manager to ignore files starting or ending with a ~ tilde,
assuming that they're temporary files (probably a botched idea)