dpkg-source: improve the patch parser

dpkg-source: improve the patch parser

* scripts/Dpkg/Source/Patch.pm (analyze): Enhance function to
parse correctly many more patches that are accepted by the patch
utility itself:
- ignore/strip carriage return of patches with Windows end of lines
- accept empty lines as contextual lines (instead of the expected " ")
- accept spaces as separator between filename and timestamp if
  there's no tab
- accept a name that differs on the +++ line if the name in --- is
  correct, and use the name in +++ if this one exists while the one
  on --- doesn't.