libmodbus v3.1.3

[Stéphane Raimbault]

Thanks to all contributors for this new release.

Next steps: merge of ASCII backend and callback feature.

I see many forks on github, if you have something to merge it's time to make a Pull Request before the v3.2.

- New bswap macros for Max OSX by Jakob Bysewski.

- Fix "wildcard address" in TCP IPv6 by Shoichi Sakane.

- Introduce offsets in modbus mappings with modbus_mapping_new_start_address.

  Thanks to Michael Heimpold and Stéphane Raimbault.

- Fix address range in random-test-client.

  Thanks to Martin Galvan.

- Add an option to disable tests compilation by Yegor Yefremov.

- Define MSG_DONTWAIT to MSG_NONBLOCK on AIX (#294).

  Thanks to Fabrice Cantos.

- Fix building when byteswap.h is not defined by Tomasz Mon.

- Add some more macros for data manipulation and documentation.

- Remove duplicate install of modbus.h (closes #290).

  Thanks to Daniel Sutcliffe.

- Move MIGRATION and README.md to dist_doc_DATA target.

- Change order of few functions in modbus RTU code.

- Add entries for modbus_rtu_[get|set]_delay in documentation index.

- Implemented runtime configurable RTS delay by Jimmy Bergström.

- Add an entry in libmodbus index page for modbus_rtu_set_custom_rts.

- Add support for user defined RTS toggle function by Jimmy

  Bergström.

- Added ILLEGAL_DATA_ADDRESS tests for modbus_write_register[|s].

  Thanks to Andrey Skvortsov.

- Update documentation of modbus_rtu_set_rts

- Fix rts signal switch time by Hiromasa Ihara.

- Improve new_rtu and set_slave documentation (related to #276).

- Fix late check of ctx in modbus_reply[|_exception] (closes #269).

- Wait the server for 1 second before running tests (help Travis).

- A libmodbus context isn't thread safe and won't be (closes #246).

- Fix buffer overflow in modbus_mask_write_register (#265).

- Minor adjustments to README about AsciiDoc.

- Export MODBUS_MAX_ADU_LENGTH and documentation (ref #241).

- Explicit check against Modbus broadcast address.

- Do not reply on broadcast requests (fixes #153). Thanks to Michael.

- Add Travis support.

- Run unit tests with standard: make check (closes #205, closes #238).

  This patch has been developed by Andrey Skvortsov, Michael Heimpold

  and Stéphane Raimbault.

- modbus_send_raw_request: limit request length (fixes #207).

  Thanks to Hanno Neuer for spotting this security flaw.

- Add new contributors to AUTHORS

- Introduce SPDX license identifiers. Thanks to Michael Heimpold.