Release preparation : helpers/Xstring.h changed to helpers/XString.h to compile on Linux and Windows OS's

- Novelec part : added automatic type of electrometer

- communicationLink structure modified
- Range : modified to use RangeUp/Down commands

no more write_read cmd but write then read instead.

Keithley DDC part ->devices are very slow (exp 485 model) so write_read cmd is splitted !

Keithley DDC part -> no more data with prefix
TODO : change all DDC files.

Novelec part updated

- Novelec part updated and tested !
- +no more compilation warnings

K_485 no config cmd supported.

- attributes management :
-> integrationTime, buffersize and triggerMode now well initialised

TODO : after a Start command
-> declare all attributes INVALID !?

- trigger mode and buffer size management added.
- TODO: DDC/SCPI
integration time for ScanServer compatibility.
SRQ management for Keithley Integration mode