Code clean up.

* Removed LLCurlRequest and replaced it's last usage with LLHTTPClient API calls.
* Deleted dead code.
* Renamed all the get4/post4/put4/getByteRange4 etc, back to their
  original name without the '4'.

indra/newview/llinventorymodel.cpp

@@ -578,7 +578,7 @@ LLUUID LLInventoryModel::createNewCategory(const LLUUID& parent_id,
 //			request["payload"] = body;
 
 //			viewer_region->getCapAPI().post(request);
-			LLHTTPClient::post4(
+			LLHTTPClient::post(
 						   url,
 						   body,
 						   new LLCreateInventoryCategoryResponder(this, callback, user_data) );