readtag.c: initial fixes for MinGW

no syslog on win32
SIGIO define missing under MinGW's signal.h
%ld expects long int
readtag.c: eliminate unnecessary debug output

Only read twice in Connect() if writing
tuxeip: fixes for winsock2

MSVC needs io.h for close() in Ethernet_IP.c
Add WSACleanup() calls after close()'s for win32
Must call WSAStartup() before using a socket under winsock
Version 2.2 was released in 1997, safe to assume we can use it instead.
Initial Clang fixes

-Wundef fix in TuxDef.h
-Wshadow in MR.c, size was already used
-Wdocumentation in ErrCodes.c
CM.c: pointer arithmetic on void* is a GNU extension
More Clang fixes

SendData.h: add extern for -Wmissing-variable-declarations
ErrCodes.c/h: format string for LogCip() should be const
AB.h: add missing enumerations