OFF v2.0.8.5 — relay-floor wallet fee (PR #30 by 9019x)

OFF v2.0.8.5 - relay-floor wallet fee (PR #30 by 9019x)

Supersedes v2.0.8.4. Adopts PR #30's relay-floor enforcement in
CWallet::CreateTransaction() and CoinControlDialog::updateLabels(),
reverting v2.0.8.4's nMinTxFee constant bump. Net effect on the
'large coin-control TXs rejected for fees' bug is the same fix,
but with no 10x overpayment on 1-49 KB mid-size TXs.

Also removes the pre-0.9 sub-cent change-bump (unreachable dead
code, tagged for removal in its own comments) and corrects four
coin-control tooltips to cite nMinRelayTxFee.

Reported and fixed by 9019x. Diagnosis credit:
https://github.com/SubGeniusFinance/Offerings-to-Cthulhu/pull/30

No consensus / net / RPC / init / miner change. Same depends/
stack and PROTOCOL_VERSION (90003) as v2.0.8.3/.4.