h3. Merge [kernels] and [java] into [pcr]

This would reduce the number of repos which have to be enabled, thus simplifying installing packages and the maintenance burden on the wiki.
Moreover, having separate, tiny repos for very specific things is not consistent with our policies for repos in general; it is confusing that these things are somehow so special they need their own repos, unless I am missing something here.

h3. Remove dead repositories

Corresponding abslibre directories:
- retired/
- unmaintained/
- ~*/
-- aurelien/
-- lukeshu/
-- megver83
-- smv