Fix ceylon-format.bat script

- Remove unicode characters, because codepages and ancient technology
- Fix multiline variable syntax – this was a huge pain to get right,
  huge thanks to @sgalles who patiently tested about a dozen attempts on
  his Windows machine while I was blindly fumbling around on Linux.

@Quintesse should probably look at this – the syntax from the example
script doesn’t seem to work.
Fix help text about error recovery

That would be some error recovery if it _destroyed_ the file… I wonder
if this detered anyone from using ceylon.formatter :D