Improve configure.ac, logging and C4SNet

Changed configure.ac to add --disable-setaffinity and fix SAC2BASE warning.

Disable USE_USER_EVENT_LOGGING by default and not create any files or logging threads when undefined, so as to speedup the common executions.

Improve reporting in detail of record types for partially matched synchro-cells.

Also give detailed type information on record and possible branching variants when a Parallel dispatcher cannot route a record, so as to be helpful to S-Net application developers.

Add a function C4SNetGetType to obtain the basic type of a field.

Add a handy function C4SNetGetString to convert an array of CTYPE_char
or CTYPE_uchar to a proper nul-terminated C string.

Add comments in the C4SNet.h header file to briefly explain each
function to S-Net application developers.