Use the w32_common keymaps in terminal-win

This should fix #476, and hopefully any other inconsistencies in how the terminal handles keystrokes, compared to how the video windows handle them.

It's a bit ugly, since `lookup_keymap_table` is in vo.c, so I had to copy it here. I'm not sure if there's a better solution, though maybe `lookup_keymap_table` and `mp_keymap` can be moved to input.h/c.