Server script to download the latest installer

As promised, I talked with enumag about the script and he sent it to me earlier today.

You can access it at http://07th-mod.com/installer.php

By default, it will guess the user platform and get the latest stable release. You can force it to go through manually using: ``http://07th-mod.com/installer.php?system=win|mac|linux&branch=pre|stable``

Example: http://07th-mod.com/installer.php?system=linux&branch=stable

Beware that using ``branch=pre`` will only work if the most recent release is marked as a pre-release. If the most recent is a stable release, it will get the stable instead of the pre-release.

Right now the guessing part doesn't work, but I believe it is because of the current changes ongoing at the releases page. Earlier today it was working fine, so it might fix itself soon enough.

The script is hosted at http://07th-mod.com/installer.php and interacts with GitHub releases. Start by examining the existing server-side logic for platform detection and release fetching. Understand how it determines 'stable' vs 'pre' branches and integrates with the project's release page. Test the endpoint with different query parameters to verify current behavior and identify the guessing issue.

Written by the indexing model from the issue text.