count DATA cells with stream ID 0 as delivered for SENDME purposes

Found while investigating 8093, but probably not the cause of it,
since this bug would result in us sending too few SENDMEs, not in us
receiving SENDMEs unexpectedly.

Bugfix on the fix for 7889, which has appeared in 0.2.4.10-alpha, but
not yet in any released 0.2.3.x version.
Turn --enable-buf-freelists off by default
Add --disable-mempools configure option
Turn --enable-mempools off by default
Add changes file for bug11476
Sandbox: allow access to stats/bridge-stats

Fix for 12041; bugfix on 0.2.5.1-alpha.
Fix a sentence that I never
Oops; permit rename with the correct filename
sandbox: Permit access to stats/dirreq-stats

This prevents a crash when rotating logs with dirreq-stats enabled

fixes 12035; bugfix on 0.2.5.1-alpha.
sandbox: Disallow options which would make us call exec()

None of the things we might exec() can possibly run under the
sanbox, so rather than crash later, we have to refuse to accept the
configuration nice and early.

The longer-term solution is to have an exec() helper, but wow is
that risky.

fixes 12043; bugfix on 0.2.5.1-alpha
sandbox: tolerate reloading with DirPortFrontPage set

Also, don't tolerate changing DirPortFrontPage.

Fixes bug 12028; bugfix on 0.2.5.1-alpha.
doc/HACKING: Improve documentation of how to bump version in maint

See discussion on 9553: Some of the build scripts don't like it when
you can't merge maint into release.
sandbox: support logfile rotation

Fixes bug 12032; bugfix on 0.2.5.1-alpha
fix a wide line
sandbox: permit gettid, sched_getaffinity

These are needed under some circumstances if we are running with
expensive-hardening and sandbox at the same time.

fixes 11477, bugfix on 0.2.5.4-alpha (where we introduced
expensive-hardening)
Eliminate #ifdef ENABLE_MEMPOOLS in packed_cell_new/free()
Merge remote-tracking branch 'andrea/bug11476'
sandbox: revamp sandbox_getaddrinfo cacheing

The old cache had problems:
     * It needed to be manually preloaded. (It didn't remember any
       address you didn't tell it to remember)
     * It was AF_INET only.
     * It looked at its cache even if the sandbox wasn't turned on.
     * It couldn't remember errors.
     * It had some memory management problems. (You can't use memcpy
       to copy an addrinfo safely; it has pointers in.)

This patch fixes those issues, and moves to a hash table.

Fixes bug 11970; bugfix on 0.2.5.1-alpha.
Documentation fix: DataDir/status/* -> DataDir/stats/*

Our documentation had the name of this directory wrong.
sandbox: allow access to various stats/*-stats files

Fix for 12064 part 1