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

linux compilation

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

- bug in Novelec part fixed (END_OF_LINE!)

MEAS? cmd changed. Now READ? is called instead.

Keithley part : support for 6517.

K_485 no config cmd supported.

range values ordered
set_range added

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

- MCCE2 (Novelec part) : methods to change the active channel to communicate with.

Tango_OMemstream removed, string used instead

- library update

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

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

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

6517 model management added and tested :
-> problem to check : no SRQ !

lib compiled on Linux platform

- minor change (std::cout removed)

- minor change (std::cout removed)

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

- command abort added for SCPI Keithleys

- command abort added for SCPI Keithleys

- minor change for integration time

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