Legacy Update: Get back online, activate, and install updates on your legacy Windows PC

This release will feel very minor on the surface, but I put a bunch of work into improving the codebase.

• Switches the file downloader library to one that seems to be a lot more stable, and reliable in every condition - slow internet, insufficient RAM, internet faster than your RAM/hard drive can keep up with, etc. It is also able to reconnect and continue if your connection drops during a download.
• Refactors the ActiveX control from the hefty Microsoft MFC framework to the lighter-weight ATL framework. This brings down the file size of the DLL.
• Uses more efficient compression on the installer (LZMA rather than Gzip), bringing the download size down even further.
• Improves error handling in the ActiveX control, so that in the unlikely case of the Legacy Update ActiveX control itself failing to do something, more useful error information will be displayed.
• Fixes installing Service Packs on Windows Vista/7 again - this was supposed to be fixed in 1.6.1 but I created another bug in the process.
• Fixes the LegacyUpdateTemp user lacking administrator permission on non-English installs of Windows, causing a "log on as an administrator" error after Legacy Update setup automatic restarts.

The massive changes in this release seem to have tripped up the exceptions Legacy Update was receiving from antivirus vendors. Currently, Microsoft and BitDefender are triggering false positives. This should be corrected soon, once both companies respond to my tickets. (Update: Microsoft Defender false positive resolved.)

• Fixes Windows Vista/7 Service Packs not installing due to a missing .exe extension on the file Legacy Update downloads.
• Legacy Update setup now requests Windows to not put the PC to sleep while it's running.

• Fixes “The parameter is incorrect.” error when launching Legacy Update from the Start menu or Control Panel on Windows 2000 and XP 32-bit.

• Fixes the Legacy Update proxy server not being configured correctly, causing connection errors (error 80072EFE) when checking for updates on Windows 2000, XP, and Vista. Fix contributed by @renodr - thanks!

• Legacy Update now configures .NET Framework to use the Windows SSL configuration. This ensures programs built on .NET can access the same websites you can access in Internet Explorer.

• When running on a processor that doesn't support later Windows Embedded POSReady 2009 updates (Intel processors prior to Pentium 4/Pentium M, and AMD processors before Athlon 64), Legacy Update will now disallow enabling POSReady updates. See #89 for more information.

• When downloading Internet Explorer 6 SP1 for Windows 2000, Legacy Update now downloads the installer for your language directly from Microsoft. Previously, this would download an English-only copy of the IE6 installer hosted by Legacy Update. Huge thanks to @stdin82 for finding live IE6 download links on the Windows Update server.

  This change was also able to be backported to earlier versions of Legacy Update. A separate “Internet Explorer 6 Downloader” helper will be launched when running from these versions.

• Fixes the Legacy Update proxy server not being removed on uninstall on Windows Vista, and Windows Update shortcuts not being restored on uninstall on Windows XP x64/Server 2003. Fix contributed by @stdin82 - thanks!

• General code cleanup: Rebuilt Windows version checking logic from scratch to avoid annoying edge cases in the NSIS WinVer.nsh library Legacy Update was previously using, and consolidated repetitive code for patches.

Yesterday, January 10, 2023, was the end of support for Windows 8.1. Legacy Update 1.5 adds support for getting Windows 8 and 8.1 up to date. As a side effect, Windows Server 2012 and 2012 R2 are also supported starting with this release, despite that these remain officially supported by Microsoft until October.

Other changes in this release:

• While updating root certificates, Legacy Update will now also enable the TLS v1.1 and v1.2 protocols, which are present but disabled by default in Windows 7 and 8, as well as in Windows XP with a POSReady 2009 update. This is an additional fix for websites not loading in Internet Explorer and other apps that use the Windows built-in networking functionality.
• Fixes crash on launch when opening Legacy Update setup on Windows XP SP3.
• Fixes Legacy Update setup not detecting the prerequisite updates required for Windows Server 2008 and 2008 R2.
• Fixes the Legacy Update shortcut incorrectly launching 64-bit Internet Explorer rather than 32-bit in some cases on Windows XP x64 Edition. Thanks to @stdin82 for helping to point out the fix for this.