Make a simple shader editor tool

[w23]

Do not depend on bonzomatic/shadertoy.
Make a simple (assembly?) shader editing tool which:

• Gives the same GL context and inputs as release intro will get, no manual editing required prior to intro build
• Monitors and reloads shader file that is being edited in an external text editor
• Provides shader compilation diagnostics
• Reads/synthesizes exported 4klang music and allows shader-music sync
• Supports timeline navigation
• Supports loops

Possible advanced features:

• Basic OSD: timeline position, framerate
• Resolution switch