Due to an include conflict between /usr/include/poll.h and
maxscale/server/include/poll.h the latter was moved to
maxscale/server/include/maxscale/poll.h.
Once 1.4 is out, all maxscale header files will be moved to that
same sub-directory. That will prevent include conflicts and also
make it easy to see which include files belong to maxscale and
which do not.
The log manager variables lm_enabled_log_files_bitmask, log_ses_count
and tls_log_info that earlier were declared separately in every
c-file are now declared in the log_manager.h header.
