Peter M. Groen / libmodbus

- protect against NULL IP address BTW
- update documentation

- allow an empty string or NULL for node argument
- protect against NULL in service argument
- new test for NULL service
- update documentation

Thanks to vgrin for the report

It's never too late to remove 261 lines of code ;)

Thanks to Marjan Tomas

Thanks to Marjan Tomas

Thank you Marjan Tomas.

Thanks to MarjanTomas.

Change API of function for libmodbus v3.2.0

Thanks to Perry Kundert for bug report and initial patches.

The report slave id function returns the number of bytes as the _return_
value, and does not include it as the first byte in the dest buffer.

Update documentation to reflect reality.  There's no missing
functionality, just slightly confusing documentation.

- add byte timeout tests (TCP backend only)
- update and improve documentation
- long timeout values are now uint32_t so it changes the API
  to disable byte timeout

Thank you AlexMaz.

https://www.securecoding.cert.org/confluence/display/seccode/DCL37-C.+Do+not+declare+or+define+a+reserved+identifier
Not applied to libmodbus constants for now...

POSIX-1.2001 for fd_set. Thanks to spider391Tang.

- update documentation
- 5 new tests
- updated NEWS file
- avoid include of time.h

The index variable shadowed a variable in the standard library causing
warnings. Renaming the 'index' variable to 'idx' resolves the issue.