Much more than usual, now that we've got a snappy build system! This
commit covers
• All .PI functions across all games
• TH02's High Score entry functions
• TH03's shots_update() and shots_render()
• All functions declared in `th04/op/op.hpp`
• TH04/TH05's bb_txt_put_8_raw(), bullet_template_clip(),
player_pos_update_and_clamp(), score_update_and_render(), and
slowdown_frame_delay()
• TH05's reimu_stars_update_and_render(), score_delta_commit(),
stage2_invalidate(), stage2_update(), and space_window_set()
Part of P0284, funded by [Anonymous] and Blue Bolt.
Finally removing that one inconsistency that dates back to 1f1847d.
Now, every file in the `th0?/` subdirectory is meant to be assembled
with `/dGAME=?`.
Part of P0002, funded by GhostPhanom.
nmlgc