add formatted "stat" command that uses data from "STATJSON"
add cumulated sell amounts to "portfolio" command

* useful for estimating dividends
cosmetics, name MPEx with its proper casing
irc is only useful in interactive mode, so lead user for better user experience
add sample config to the .gem package
do not try to execute empty command in interactive mode
leave trailing zeros in btc notation to be always 8 digits after the dot
show total before buy or sell orders
log trades in trades.log file by using statjson and improve portfolio
prepare 0.6.0 release