PetPlugin: fixed some stupid mistakes in implementation of #119.
Merge pull request #121 from rexim/proposal-implementation-mistakes-fix

PetPlugin: fixed some stupid mistakes in implementation of #119
PetPlugin: pet transfer command. Close #118.
PetPlugin: update help.
PetPlugin: fix database structure.
PetPlugin: fix sign.
PetPlugin: standartize command processing.
PetPlugin: add rating command. Close #123.
PetPlugin: changing the nick now costs 1PTC.
MarkovPlugin: fix negative or zero argument for say command. Close #100.
Configuration: whitespace cleanup.
PetPlugin: fix bug with payments.