*) Support for typedsafe optional functions - that is functions exported by optional modules, which, therefore, may or may not be present, depending on configuration. See the experimental modules mod_optional_fn_{ex,im}port for sample code. [Ben Laurie] *) filters can now report an HTTP error to the server. This is done by sending a brigade where the first bucket is an error_bucket. This bucket is a simple bucket that stores an HTTP error and a string. Currently the string is not used, but it may be needed to output an error log. The http_header_filter will find this bucket, and output the error text, and then return AP_FILTER_ERROR, which informs the server that the error web page has already been sent. [Ryan Bloom] *) If we get an error, then we should remove all filters except for those critical to serving a web page. This fixes a bug, where error pages were going through the byterange filter, even though that made no sense. [Ryan Bloom] *) Relax the syntax checking of Host: headers in order to support iDNS. PR#6635 [Tony Finch] *) Cleanup the byterange filter to use the apr_brigade_partition and apr_bucket_copy functions. This removes a lot of very messy code, and hopefully makes this filter more stable. [Ryan Bloom] *) Remove AddModule and ClearModuleList directives. Both of these directives were used to ensure that modules could be enabled in the correct order. That requirement is now gone, because we use hooks to ensure that modules are in the correct order. [Ryan Bloom] *) When SuExec is specified, we need to add it to the list of targets to be built. If we don't, then any changes to the configuration won't affect SuExec, unless 'make suexec' is specifically run. [Ryan Bloom] *) Cleaned out open_file from mod_file_cache, as apr now accepts the APR_XTHREAD argument to open a file for consumption by