 + ept-cache reindex (rebuilds all indexes, requires root)
 + ept-cache dumpavail (with debtags and popcon, and TFIDF uniqueness and all available info)
 + ept-cache search (fast with xapian, or slow with apt, but stemmed?)
ept-cache tagsearch (smart search of tags)
ept-cache similar (with xapian, or xapian+tags, or ?)
ept-cache smartsearch (with xapian, interactive)

If xapian is used and has keywords, reduce the default limit on search as
xapian gives relevant results first.

Sorting.
