Added version roadmap to get my act together

docs/changelog/roadmap.md

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+# Planned features for 0.10.0 final
+
+## Reverb/Delay/Chorus/Flanger effect (Delaylines) 
+
+* Status: in progress.
+
+## Audio support
+
+* Status: mostly works
+
+### MIDI sequencer
+
+* MIDI 1.0 status: written, needs implementation
+* MIDI 2.0 status: for later versions (0.11.0?).
+
+### Audio development toolkit
+
+* Status: MIDI sequencer needs implementation.
+* Make music editor for a later version (0.11.0?).
+
+# Features planned for later
+
+## GPU rendering
+
+It's likely possible to do pixel perfect graphics without resorting to compute. It needs the followings:
+
+* Turn off texture filtering (possible at all OpenGL versions).
+* Set rendering resolution (likely needs rendering to texture).
+* Use a 256*256 texture for color lookup (likely possible in even the oldest GLSL version).
+
+Added benefits are speed (10 000+ objects per frame!), the possibility of low-res 3D graphics, and easy implementation of transformable sprites.