With the upcoming `#include` cleanup, it finally makes sense to split
off all graphics-related code into its own header. In turn, it makes
more sense to store all of these future master.lib headers in, well,
the master.lib directory, which provides a new 8 characters for their
file names. Turns out that the rationale I gave for the root directory
placement in 8266bbd didn't hold up 3½ years later…
(Also, the `pc98.h` declarations will eventually be split into
`game/coords.hpp` and something in `platform/x86real/pc98/`.)
Part of P0284, funded by [Anonymous] and Blue Bolt.
This commit covers
• TH02/TH03/TH04/TH05's frame_delay() and frame_delay_2() (finally!)
• TH02/TH03/TH04/TH05's game_init_main()
• TH02's graph_copy_rect_1_to_0_16()
• TH03/TH04/TH05's cfg_load_resident_ptr()
• TH05's piano_setup_and_put_initial() and piano_render()
Part of P0264, funded by [Anonymous] and Blue Bolt.
nmlgc