merge r3454, r3455, r3486, r3496, r3519, r3523: SSI fixes: *) use content type of the parent request in SSI stub block output instead of default one *) SSI %s timefmt has no timezone offset *) change ngx_http_ssi_filter and ngx_http_charset_filter order *) do not store an encoded variable value as a new cached variable value *) fix SSI include stub for valid empty responses *) allow to use $uid_got in SSI and perl module