Several fixes and improvements in SendSystemInfoDialog:

- do not show memory in MB, show it in GiB rounded to one decimal place
- when sending fails, the HTTP error code is not presented to the user (it is logged though)
- when the user cancels the sending, no extra "sending cancelled" message is shown
- in case there is no internet connection, the dialog is not shown at all
- a 6 second timeout for a case that connection is lost during sending
- the dialog is only shown when the wizard does not show on startup

src/slic3r/Utils/Http.hpp

@@ -58,6 +58,8 @@ public:
 
 	// Sets a maximum connection timeout in seconds
 	Http& timeout_connect(long timeout);
+    // Sets a maximum total request timeout in seconds
+    Http& timeout_max(long timeout);
 	// Sets a maximum size of the data that can be received.
 	// A value of zero sets the default limit, which is is 5MB.
 	Http& size_limit(size_t sizeLimit);