Log Message:
Updated url2pkg to 2.1.

Changes since 2.0:

- Made the dependency detection for Perl modules work again. The code
  does not assume to be run in a special directory anymore.

- Perl modules that use the prompt() function to query the user
  interactively can be handled. All questions are assumed to be answered
  by just pressing <enter>.

- Made url2pkg more robust when interpreting the output of MakeMaker.pm.
  Many Perl modules write additional things to stdout during the
  generation of the Makefile.

- The language for the *.f files is "fortran", not "f".

- Fixed the regular expression for prdownloads.sourceforge.net links, so
  that the distfile name is properly extracted.