[Grml] Debian repos based on locale

[Mark]

Default apt sources for grml are .de & .at domains.  For grml proper,
ok.  For external Debian packages, default apt sources based on locale
would be nice.  (Debian.org subdomains make this fairly easy, yes?)

The user should get continental selection between Europe, Africa, Asia,
North America, South America.  The big problem is going over ocean
cables for apt updates.

No need for separate files.  Have all repos listed in one file,
commented out.  Scripts like grml2hd can comment-in as appropriate to
finalize.

M.