update r->buffered after processing SSI command,
the bug has been probably introduced in r2378

fix case of partially matched patterns on buffer border in sub_filter

remove r->zero_in_uri

cache related fixes:

*) do not cache response if it has "no-store" or "private"
   in "Cache-Control" header
*) proxy_no_cache and fastcgi_no_cache

use lstat() for WebDAV DELETE, COPY, and MOVE to handle symlinks

opening files fixes:

*) use non-blocking open() not to hang on FIFO files, etc.
*) do not log misleading errno in "not a regular file" error

rewrite fixes:

*) escape ampersand in argument while rewrite
*) autodetect redirect if URI is rewritten to a string starting with $scheme