nutdrv_qx: add basic support for more complex UPS answers

Add support (also in 'TESTING' mode) for '\0' chars in raw UPS answers and the ability to preprocess answers before anything else (e.g.: for CRC, decoding, ...).
Increase verbosity of USB subdrivers and serial communication.
Always print also the return code when dealing with an error.
Update all subdrivers accordingly, bump versions.
nutdrv_qx: update docs about added support for more complex UPS answers
nutdrv_qx: add Voltronic-QS-Hex subdriver (protocol=voltronic-qs-hex)

A subdriver using a protocol, specific to UPSes manufactured by Voltronic Power, partially Hex-encoded (e.g. 'QS' reply) and supporting some megatec commands.
nutdrv_qx: add new 'fabula' USB subdriver

Add a new USB subdriver ('fabula') to support models manufactured/rebranded by Fideltronik and accompained by UPSilon2000 software.

Reference: http://lists.alioth.debian.org/pipermail/nut-upsuser/2014-June/009059.html
nutdrv_qx: improve the USB matching procedure

Consider also the iManufacturer/iProduct strings when checking devices (if subdriver is not specified) to assign the right subdriver in case the VID:PID couple is not specific enough.