fix user difficulty in username
Merge pull request #114 from iongchun/fix-userdiff

fix user difficulty in username
fixed crash when running in --debug mode
modulate share difficulty to prevent any node from producing more than 5% of shares
avoid breaking asicminer BE blade with too-long getwork response
fix litecoin testnet target high for testing
print notice of imminent switchover
dynamically adjust share difficulty to prevent payouts below dust threshold
only duplicated Share class so next few changes are visible
added new share class
changed new share to delay payouts 1 share
increased last_txout_nonce length from 4 to 8 bytes
use OP_RETURN in new shares
change SHARE_PERIOD and SPREAD to new values on switch to new share implementation
incremented network version to 13
store total share count and work within shares
simplified transaction preforwarding by requiring shares to be accompanied by only their _new_ transactions, instead of all the transactions they use
updated bootstrap addrs
increased maximum difficulty multiplier to 30
added year as an allowable time unit for display