core: proper destroy of tcp connection at shutdown

- don't access connection fields after freeing structure
xlog: clean exit at startup in case on error looking up facility
xhttp: wrong variable was used for checking memory allocation
tm: clean contacts in case of failure in t_load_contacts()
tls: free the file path clone when all went ok
textops: cleanup on error parsing methods at startup
pv: removed mistaken pkg_malloc() left for $cnt()
sipcapture: free proper db_url field and destroy capture mode data list
rr: free forgotten allocated local variable trans in case of error
nathelper: free local variable if getting anchor for contact header fails
mi_rpc: don't access fields in structure after free in mi_rpc_async_close()
htable: init allocated memory after checking parameter

- avoid useless operation and extra check for leak
exec: free local variable if there is no more memory in next attempt
Makefile.defs: version set to 4.2.0-dev5