implement public-inbox-purge tool

Expose the ->purge functionality of V2Writable for rewriting
git history to permanently purge messages from history.  This
may be necessary for legal reasons.

Usage:

	# requires ~/.public-inbox/config
	public-inbox-purge --all </path/to/message-to-purge

	# good for testing with unconfigured inboxes:
	public-inbox-purge $INBOX_DIR </path/to/message-to-purge

1 files changed, 2 insertions, 0 deletions

diff --git a/MANIFEST b/MANIFEST
index 5ac85c3f..886ae6b2 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -128,6 +128,7 @@ script/public-inbox-init
 script/public-inbox-learn
 script/public-inbox-mda
 script/public-inbox-nntpd
+script/public-inbox-purge
 script/public-inbox-watch
 script/public-inbox.cgi
 scripts/dc-dlvr
@@ -198,6 +199,7 @@ t/psgi_multipart_not.t
 t/psgi_search.t
 t/psgi_text.t
 t/psgi_v2.t
+t/purge.t
 t/qspawn.t
 t/reply.t
 t/search-thr-index.t