Add URL redirection support, non-flickering text and meaningful error messages to ReactOS Applications Manager

This patch improves the following areas of rapps:

1. Adds message boxes for WinINet problems; shows info about things like timeouts and lack of DNS resolution. Useful to quickly diagnose connectivity problems.

2. Adds message boxes for HTTP status codes; shows interesting things that the target server might spit like 404 (Not found), 403 (Moved), 5XX (I don't know what I'm doing). Useful for finding out dead links.

3. Fleshes out the downloading back-end (which uses WinINet behind the scenes) to support redirection, limited to 6 tries to avoid infinite loop traps. This makes it easy to use tricks like the "?nowrap" parameter for Sourceforge, skipping the scamware downloader.

4. Stop updating the URL text field in the download progress dialog on every progress refresh, getting rid of that lame text flickering. Instead of that it just does it on dialog creation. Cosmetic, but annoying.

Currently when there's any problem with the download you don't quite know if there was a connectivity problem on your side or a server hiccup, it just vanishes without notice!

This is specially frustrating when you are away from the keyboard expecting to see your long download finished and you are greeted instead by an inactive and nondescript rapps with no signs of what could have happened some minutes ago.

[Coming soon to a Jira near you]