r22 fixes quite afew issues, introduces --all

Written for Ubuntu maintenance check by Nick Barcet on 2009-04-15

A few people wanted to be able to generate a full list of packages that are maintained and now for how long. This is now possible with the --all option.
Fixes include the previous omission of packages that were in main but not directly used in desktop, server or kubuntu seeds. They are now listed as 18mo maintenance by default.
Also added some code so that kernels shoudl always be marked with their correct maintenance life.