cran2deb: initial stab at dependencies on R packages. license tidying.

cran2deb: initial stab at dependencies on R packages. license tidying.

Needs testing in a pbuilder suitably set-up.  Handles R's default
packages in a rather hacky way (list all of them explicitly).

Generates Build-Depends: and Depends: as almost identical since all R
packages are typically required during the build phase.

Add licenses: X11, Mozilla Public License
Improve version regexp and recognition of many Artistic licensed
packages.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/cran2deb@24 edb9625f-4e0d-4859-8d74-9fd3b1da38cb