Forbid TunneledDirConns 0 and PreferTunneledDirConns 0 if being a HS

Fixes bug 10849; bugfix on 0.2.1.1-alpha (I believe)
Stop leaking memory in error cases of md parsing

When clearing a list of tokens, it's important to do token_clear()
on them first, or else any keys they contain will leak.  This didn't
leak memory on any of the successful microdescriptor parsing paths,
but it does leak on some failing paths when the failure happens
during tokenization.

Fixes bug 11618; bugfix on 0.2.2.6-alpha.
Merge remote-tracking branch 'public/bug10849_023_bruteforce' into maint-0.2.3
Downgrade bug 7164 warning to INFO

The 0.2.5.x warning is the one that might help us track this down; the
warnings in stable are just annoying users over and over and over.