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.

 Bug : for DDC devices, the status returned an error "Invalid staus string", now fixed.

Tango_OMemstream removed, string used instead

- DDC status show only errors if any
- added command to get DDC model configuration

- minor change (std::cout removed)

- SRQ management changed :
* ReadStatusByteRegister method added
* IsSrqLineUP added

- Integration Mode available for DDC/SCPI devices
- tests done with a K617 (DDC) and a K6485 (SCPI)

- integration mode OK (tests done with K_486)

- TODO: DDC/SCPI
integration time for ScanServer compatibility.
report config for all DDC
add configuration in SCPI start command

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