Version 0.24 released. Gradual load and inter-url timeouts

* Smooth mode now respects the interleave timeouts between urls in msec.
When an interleave timeout is specified as 0, next url or next action of
such clients is scheduled immediately without timer-queue scheduling.

* Added support for gradual increase of clients number at the loading start. Use tag CLIENTS_INITIAL_INC in GENERAL section to specify the number of loading clients to be added each second till the total client number, specified by CLIENTS_NUM tag.

* Advanced to the newest libcurl version 7.16.1 to fix several FTP and multi-handle issues

THE NEXT BOMB promised by Michael Moser is
hyper-mode with support of tens of thousand of clients for a single batch (thread). This is what
Michael is developing right now.