graph_sdl: move industrial amounts of code to graph_sdl

Finally got rid of all that damn cruft occupying main. Now everything is handled by graph_sdl. All the inputs, everything. Much better. Also using a signal handler now. So yeah. Really thinking of skipping 0.2. As in numerals. Yep, going 0.3 now. And I plan to release it in a week or two at most.