Fixed it (hopefully)

Was looking through some old backups a while back and found the source code to this old thing. This means that I can finally fix a lot of the issues that plague it.

The main changes in this version are;

• The accumulator actually initialises to 0 now like it's supposed to.
• Mouse tracking in the editor works much better
• You can now drag the mouse in the editor
• The editor also now features a simple overlay to make it easier to use. It can be toggled with tab.
• Files now save/load with a .4bd file extension to prevent confusion. It's still an INI file internally, and you can just rename any old files and it should load fine.

The key word here is "should". There's a significant risk that some other implemenation errors slipped by me while I was making the update. Tell me about them and I might be able to fix them in the future.