Restore NSIS installation script

[AldoMX]

Historical Context

When I started StepMania AMX more than 15 years ago, I didn't know how code or use source control. This repo is an attempt to reconstruct the timeline, so I will be rewriting history and force pushing changes.

What needs to be done?

Review each one of the ~ 600 commits, and update the stepmania.nsi file to apply changes in the exact point in time where they were introduced.

Stretch goals

Create releases for every legacy version.