If the new URL encoded path is found then it has precedence over the '%' escaped
path. In case none of both is found the new URL approach is used.

This is fully handled within the buffers `save` domain.

…cess

SafeWrite() will create a temporary intermediate file.

…le()`

- extract the open logic into `openFile()` and return a `wrappedFile`
- extract the closing logic into `Close()` and make a method of `wrappedFile`
- rename `writeFile()` into `Write()` and make a method of `wrappedFile`

This allows to use the split parts alone while keeping overwriteFile() as simple
interface to use all in a row.

As advantage we don't need to synchonize them any longer and
don't need further insufficient lock mechanisms.

Now the main go routine takes care of the backup synchronization.

…ails