* introduce a new rrd_create_r2 call to fix the no-overwrite api mess

* introduce a new rrd_create_r2 call to fix the no-overwrite api mess
* various fixes to new rrd_cached comands as suggested by kevin
  1. Remove opt_no_overwrite and the rrd_create_set_no_overwrite function as they are ugly.  Make opt_no_overwrite a local var.
  2. Add 'no_overwrite' param to the rrd_create_r and rename as rrd_create_r2, add rrd_create_r  that calls rrd_create_r2 with a 0 for the no_overwrite function, preserving the API parameter format but allowing an extended arg list that can be used by rrd_create and rrd_handle_request_create
  3. Add -O option to rrdcached command line to force no-overwrite on any creates
  4. Add -O option on create via rrdcached to optionally add no-overwrite (cannot remove it is it was previously set at start)
  5. Fix rrd_handle_request_last to check the queue instead of forcing a flush.  Remove -no-flush option from LAST command since it is now no longer relevant as we're querying the cache chain
  6. Fix ulong/unsigned long issue for compilation under windows
  7. Change rrd_handle_request_create to only accept timestamp parameters, not at-syntax, in order to be threadsafe.  This is no  loss since the rrd_client already pre-parses any at-style syntax
  8. Reinstate missing free() in rrd_info.c and rrd_last.c

-- steve shipway

git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@2136 a5681a0c-68f1-0310-ab6d-d61299d08faa