Release notes 0.18.3

Bitcoin ABC version 0.18.3 is now available from:

https://download.bitcoinabc.org/0.18.3/

This release includes the following features and fixes: - Remove support for Qt4 - Upgrade reproducible build to use Qt 5.9.6 - Improve SHA256 performance using SSE4.1, AVX2 and/or SHA if available. - Add a mode argument to the getmemoryinfo RPC call to query malloc_info from the system if available. - Updated univalue library to version 1.0.4 - Disable safe mode by default - Added autocomplete to 'help' in RPC console - Deprecated estimatefee RPC command - Improved help message for backup wallet RPC - Various bug fixes that improve node stability and performance - Backport getblock RPC's new verbosity mode from bitcoin core for retrieving all transactions of a given block in full. - Added parkblock/unparkblock RPC commands and 'parked' state to getchaintips RPC - RPC listreceivedbyaddress now accepts an address filter - Backport combinerawtransaction RPC from bitcoin core to combine multiple partially signed transactions into one transaction.