Major changes to support multiple distfiles in templates.

Each template now needs to use $distfiles that accepts the full
URL to download the distfile and old $extract_sufx is now merged
on it, but this must be separated by the '@' character. Example:

distfiles="http://www.foo.org/blah-6.2@.tar.gz
http://www.foo.org/blob-1.0@.tar.bz2"

If distfiles contains multiple files defined, $wrksrc is now
mandatory.

--HG--
extra : convert_revision : 1c3fa35f148af8323ce3cbcf5732104960de6bc4

templates/zip.tmpl

@@ -1,9 +1,7 @@
 # Template build file for 'zip'.
 pkgname=zip
 version=2.32
-distfiles="zip232"
-extract_sufx=".tgz"
-url=ftp://ftp.info-zip.org/pub/infozip/src
+distfiles="ftp://ftp.info-zip.org/pub/infozip/src/zip232@.tgz"
 build_style=bsd_makefile
 make_build_args="-f unix/Makefile"
 make_build_target="generic_gcc"