Fixed bug #418: Scheduled Downtime Notifications Resent On Nagios Restart/reload

This was accomplished by adding a member to the downtime structure which 
records whether the start-of-downwtime notification has been sent. This is
also recorded in the status.dat and retention.dat files, the latter
so it can be read back in on Nagios restart.
Change log for svn revision 2600, bug #418 fix
Fixed bug #369: status.cgi crashes with segfault when there are german ulauts (äöüß) in the hostname or the servicename
Fixed bug where selecting Command Expansion from Configuration CGI page would display commands instead
Updated CGI utility functions to support UTF-8 characters

Specifically the escape_string() function in cgiutils.c was updated. 
In order to support this we needed to set the encoding which is set 
using setlocale(). 

Because setlocale() specifies both the language and the encoding, 
the function that reads the CGI variables now calls a function to 
parse the HTTP_ACCEPT_LANGUAGE variable and attempt to set the 
locale based on the user's preferred language and locality.

This wasn't really necessary because all we really needed was to 
set the encoding to UTF-8, but it may be useful in the future and 
is less ethnocentric than just blindly setting the locale to 
en_US.utf8. :-)
Fixed bug #424: Nagios Core 3.4.4 seg fault (core dump) on restart after removing config for running service 

I suppose since the log message says we're ignoring a service that no
longer exists, we should really ignore it.
Update Changelog for fix for bug #424
Clean up function declaration
Update version number for 3.4.5rc1
Fixed bug #403: The configuration page of the webui doesn't use entity encoding when displaying the command expansion item
Updated html_encode() to correctly encode characters outside the ASCII character set
Update version number for 3.5.0rc1