Improvements in silent resume

When pausing/resuming task (either manually or by exiting CH while processing and re-launching program again) the operation should resume the processing silently (i.e. without asking for overwriting existing file if writing to that file would be silent before pausing).
There is an exception in this rule currently - when CH processes the last part of the file, the destination file might become a bit bigger than source file. If the task will be paused at that moment and resumed, the replace dialog will appear asking to overwrite the bigger file.
To avoid that, CH needs to store additional information in the database regarding finalizing file.