Rewrite byterange handling so that:

 * the syntax is parsed properly
 * unsatisfiable requests cause a 416 error
 * the API is completely preserved

PR:             6973
Submitted by:   fanf, wrowe
Reviewed by:    jim, stoddard, trawick, (dirkx, martin)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@87702 13f79535-47bb-0310-9956-ffa450edef68