Stop accepting 0.2.2 relay uploads for the consensus.

Resolves ticket 11149.
Test code for implementation of faster circuit_unlink_all_from_channel

This contains the obvious implementation using the circuitmux data
structure.  It also runs the old (slow) algorithm and compares
the results of the two to make sure that they're the same.

Needs review and testing.
Defensive programming: null [pn]_chan,circ_id in circuit_mark_for_close_

Doing this as part of the patch for #9683 to prevent possible bugs
down the line
Take out remaining V1 directory code.
Appease make check-spaces
Add changes file for bug #11235
Work on the changelog for 0.2.5.3-alpha some more
copy-edit the 0.2.5.3-alpha changelog even more
fix a few grammar things, and deprecate 'servers' and 'nodes'

also clarify a few explanations. so far so good!
use the formatting from 0.2.4.21 for the 0.2.4.21 changelog stanza
missing colon
sort stanzas by interest, and sort by version within stanzas

(users want to know about client fixes before they want to know about
unit test fixes.)
extract some changelog principles into doc/HACKING
Merge remaining changes/* items into ChangeLog

(Not taking bug11235 since it's a whitespace fix)
Fix unittest compilation with --disable-curve25519

This is a fix for 9700, which we already fixed in 0.2.5.x, but which
got left in 0.2.4.x.

This is a partial backport of a0a855d586d99540277014ccd3
Merge remote-tracking branch 'origin/maint-0.2.4'

This is an "ours" merge, taking nothing, since we already had the
changes that were in a83abcf5ee5cb8fe245bc97e0
Increment version to 0.2.5.3-alpha
Set a date in the changelog
Actually I am releasing tonight
bring hacking more up to date