Check spawn_func() return value

If we don't, we can wind up with a wedged cpuworker, and write to it
for ages and ages.

Found by skruffy.  This was a bug in 2dda97e8fd898757, a.k.a. svn
revision 402. It's been there since we have been using cpuworkers.
More hacking around spawn_func issues

This time, we use a pthread_attr to make sure that if pthread_create
succeeds, the thread is successfully detached.

This probably isn't the big thing going on with 4345, since it'd be
a bit weird for pthread_detach to be failing.  But it's worth
getting it right.
Remove TunnelDirConns and PreferTunnelledDirConns

These options were added back in 0.1.2.5-alpha, but no longer make any
sense now that all directories support tunneled connections and
BEGIN_DIR cells.  These options were on by default; now they are
always-on.

This is a fix for 10849, where TunnelDirConns 0 would break hidden
services -- and that bug arrived, I think, in 0.2.0.10-alpha.
Give specific warnings when client-side onionskin handshakes fail

Fix for bug9635.
Better log message when writing a CR in text mode on windows

Help to diagnose #11233
Make compilation of tor_memdup_nulterm() with dmalloc

Fixes bug 11605; bugfix on 0.2.4.10-alpha.
Forbid TunneledDirConns 0 and PreferTunneledDirConns 0 if being a HS

Fixes bug 10849; bugfix on 0.2.1.1-alpha (I believe)
Fix memory leaks in test_circuit_timeout

Found with valgrind.
Fix memory leak in test_onion_queues
Fix memory leak in test_geoip
fix uninitialized memory reads from test_geoip_with_pt. Found with valgrind
Fix memory leaks in test_cntev_append_cell_stats
Fix memory leak in test_util_asprintf
Fix memory leak in unittest helper function.
Fix a leak in test_buffer_allocation_tracking
Memory leaks in test_config_addressmap
Fix leaks in test_exit_policy_dump_to_string
test_cntev_append_cell_stats now no longer leaks
Fix numerous leaks in test_pt.c

I didn't find a managed_proxy_free() function any place; shouldn't
there be one?
Fix leaks in test_dir_formats