Class represents a single log cache
Some implementation notes
Requesting an item from cache:
select changeditems.revision,changeditems.changeditem,logentries.author from changeditems,logentries where (changeditems.changeditem GLOB '<item>/*' or changeditems.changeditem = '<item>') and logentries.revision=changeditems.revision
item must be clean, eg., no / at end.
