webserver: fix hardcoded GET error response
fix strt2int64 et. al. to parse 64 bit and not 32 bit
cosmetics: fix some whitespaces in CWebServer
webserver: update MIME type support
webserver: add AddHeader utility method
webserver: only cache JavaScript and CSS files for a day (same as HTML)
webserver: fix 64-bit print format for Content-Length
webserver: add GetLastModifiedDateTime() utility method
webserver: add support for Range requests (Accept-Ranges, Range, If-Range, Content-Range)
webserver: add optional debug logging about request and resposne data
Merge pull request #2614 from Montellese/webserver_range_support

webserver: support for HTTP Range handling (makes HTTP streams seekable)