http_dav.c: support DAV:getlastmodified on calendar/addressbook collections
httpd.c: Per latest version of httpbis part2, and Expect header in a HTTP/1.0 request MUST result in a 417 (Expectation Failed) response
http_proxy: always need to read client request body when piping (even if backend rejects request based on preconditions)
http_proxy.c: remove redundant variable
http*.c: - split parsing of message framing headers from reading of message body
	- moved bofy disposition flags from transaction_t into body_t
http_proxyd.c: don't leak SASL conn when "pinging" backend - found by Valgrind
httpd.c: split parts of http_auth() functionality into proxy_auth() and auth_success()
httpd.c: allow an authenticated admin to proxy as another user without reauthenticating
http_proxy.c: when "pinging" a backend just (re)authorize rather than completely reauthenticating
Revert "http_proxy.c: remove redundant variable"

This reverts commit f622d01c206a6630e0aac53dc91ca9b0885777d0.

Conflicts:
	imap/http_proxy.c
http_rss.c: squash signed/unsigned warning
httpd.c: only allow proxy authz on Murder backends
global.c: canonicalization input and output buffers may overlap
backend.c: can't free() local SASL callbacks before SASL ctx has been disposed
http_proxy,c: can't free() local SASL callbacks before SASL ctx has been disposed
http_caldav: nits in store_resource()
http_carddav(): return Last-Modified when we store a resource
configure.in: (hopefully) support newer name for AFS com_err library
changes.html: getting ready for beta7
caldav_db.c: properly construct time span of a component based on type and rules in RFC 4791 Sec 9.9