Peter M. Groen / libmodbus

This time the change is definitive :)

- upgrade to WAF 1.5.3
- smaller WAF scripts
- fix using of modbus.h with WAF
- updated configure.ac and Makefile.am files
- change include paths in test files

- remove header and checksum length from modbus_param_t
- use new const tables

- new functions modbus_slave_init_listen_tcp, modbus_slave_accept_tcp,
  modbus_slave_slave_receive.
- removed printf in modbus.c: 'Connection closed'
- new slave test, bandwith-slave-many-up
- updated build scripts
- updated MIGRATION document file

- reduce the number of variables to store return values (status,
  query_ret and response_ret -> ret)
- add some comments

- s/datas/data/
- the warning is now an error
- add some checks in modbus.c
- add unit tests
- remove the TODO item
- minor 80 columns changes

libmodbus does not link with c++ code.

Pahole tool by Arnaldo Carvalho de Melo has been used to found this problem.

It's slower to pass non aligned values.

- Reduce the max message length to 256 (PI_M300)
- s/size/length/

- cleanups in offset/resp_length vars
- cleanups in comments
- add FORCE_MULTIPLE_COILS in manage_query

- declare some functions static
- use uint8_t and uint16_t in various places to reduce memory use, the transition is not complete and will break compilation of some applications
- add some new functions to get/set bits from one or many bytes:
  o set_bits_from_byte
  o set_bits_from_bytes
  o get_byte_from_bits
- the server (slave) detects a connection closing

With TCP, automatic reconnect on error may not be desired.
It's now possible to adjust the error handling mode.

Need testing.

- separate tests directory
- regroup modbus.h and modbus.c in the same dir
- updated waf scripts
- updated autotools files
- bump application version to 1.9.0
- bump library number to 2.0.0