Fixed utf8 decode (ticket #25).

Patch by Alexey Kuts.

Autoindex fixes:

*) Autoindex: escape '?' in file names.

   For files with '?' in their names autoindex generated links with '?' not
   escaped.  This resulted in effectively truncated links as '?' indicates
   query string start.

   This is an updated version of the patch originally posted at [1].  It
   introduces generic NGX_ESCAPE_URI_COMPONENT which escapes everything but
   unreserved characters as per RFC 3986.  This approach also renders unneeded
   special colon processing (as colon is percent-encoded now), it's dropped
   accordingly.

   [1] http://nginx.org/pipermail/nginx-devel/2010-February/000112.html

*) Autoindex: escape html in file names.

Various fixes related to error messages:

*) Removed old warning that suggested to use "server_name_in_redirect off"
   (now the default) in place of no longer supported "server_name *".

*) Fixing directive name in error message if types hash size is not enough.

*) Replaced "can not" with "cannot" and "could not" in a bunch of places.
   Fixed nearby grammar errors.

*) Overhauled error messages.

Move SO_ACCEPTFILTER and TCP_DEFER_ACCEPT checks into configure.

NetBSD 5.0+ has SO_ACCEPTFILTER support merged from FreeBSD, and having
accept filter check in FreeBSD-specific ngx_freebsd_config.h prevents it
from being used on NetBSD.  Therefore move the check into configure (and
do the same for Linux-specific TCP_DEFER_ACCEPT, just to be in line).

error_log related fixes:

*) Complain on invalid log levels.

   Previously only first log level was required to be correct, while
   error_log directive in fact accepts list of levels (e.g. one may
   specify "error_log ... debug_core debug_http;").  This resulted
   in (avoidable) wierd behaviour on missing semicolon after error_log
   directive, e.g.

       error_log /path/to/log info
       index index.php;

   silently skipped index directive and it's arguments (trying to
   interpret them as log levels without checking to be correct).

*) Fixed configuration summary and manpage contents for the special
   --error-log-path=stderr case.

Miscellaneous fixes:

*) Fix of names of the referer hash size directives introduced in r3940.

*) Cosmetics: replaced NGX_CONF_TAKE1 to NGX_CONF_FLAG for "sendfile"
   and "chunked_transfer_encoding" directives, to be in line with all
   directives taking a boolean argument.  Both flags will ensure that
   a directive takes one argument.

*) Improved ngx_parse_time() code readability.

*) Preallocating exact number of default MIME types entries.

*) Stylistic change in checking the boolean expression.

*) Replaced magic constants representing default values of some directives
   with appropriate #define's.

*) Fixed grammar in a comment.

*) Fixed two minor bugs in "types" parsing code.

open_file_cache related fixes:

*) Bugfix: open_file_cache lost is_directio flag.

On file retest open_file_cache lost is_directio if file wasn't changed.
This caused unaligned operations under Linux to fail with EINVAL.
It wasn't noticeable with AIO though, as errors wasn't properly logged.

*) Bugfix: open_file_cache did not update file info on retest.

If file inode was not changed, cached file information was not updated
on retest.  As a result stale information might be cached forever if file
attributes was changed and/or file was extended.

A new fix for the case when ssl_session_cache defined, but ssl is not
enabled in any server. The previous r1033 does not help when unused zone
becomes used after reconfiguration, so it is backed out.

The initial thought was to make SSL modules independed from SSL implementation
and to keep OpenSSL code dependance as much as in separate files.