temporary readme with code layout annotations

main.c - init + main loop
kernel.c - core dispatcher

video.c - low level graphics and principle backend stuff
audio.c - low level audio backend stuff
input.c - low level input source

sfx.c - sound effect interface
music.c - music player interface
seq.c - sequencer for music
synth.c - generates sound
org.c - instruments
dsp.c - dsp routines

util.c - reporting and other utility functions
rng.c - random number generator

graphics.c - drawing api exposed to game modules
text.c - drawing nice variable width text
stage.c - the static platforms
entity.c - 

loader.c - reading from game data files
zip.c - zip file reader
midi.c - midi file reader

splash.c - game modules
intro.c
title.c
inner.c
iotest.c
soundtest.c