Leading or trailing white space characters in file names

[Roland Melkert]

We also should decide whether it's valid to have white space before the line type number at the beginning of the line. I think this is also ambiguous.

I think if we go with the tokens separated by with space text above, leading white space on a line is automatically valid. The only exception is the file name which at it start 'disables' the normal white space / token behavior.