Refactoring of config options loading.

Added func s_opt_addnew() that reads, allocates and adds the optinons to
the options hashtable.
HTTP requests now handled in s_process_client() per thread.
Removed unused opt var.
Commented out ASSERT that breaks DEBUG runtime.
Added uri parsing callback.

Uri is part of the http_request_t type. Each web_client_t struct
allocates a http_request_t that holds all HTTP request information.