detect incorrect capacity of SD card

[landroni]

Please add in flashbench functionality to detect incorrect capacity of SD card, like this tool:

http://www.heise.de/software/download/h2testw/50539

which can be used to detect such cards, but works on Windows only.

[ArcolaJasper]

There is an open source alternative to h2testw called F3:

http://oss.digirati.com.br/f3/