Fix error with whitespace at end of file

The VTK file reader caused an error to be thrown when reading a file that had a METADATA section at the end of the file. The problem was that the METADATA section had some whitespace after its last line (which is probably typical). This caused an eof check to pass and then a subsequent search for a token to fail.

The solution was to eat the whitespace after the METADATA section to get the reader at the next token or in eof condition if it is at the end of the file.