Make sure we start off with null() temp vstrings

See issue #31. This should avoid the reported crash,
but the tests I've tried don't trip the segfault.
But anyway, add two tests for sax with double
parsing.
Reduce length of comment to comply with Fortran standard.
Merge pull request #33 from paulromano/fix_line_length

Reduce length of comment to comply with Fortran standard.