Converts the given scancode to an ASCII character for that key (mangling Unicode values), returning the
unshifted uncapslocked result of pressing the key, or zero if the key isn't a character-generating key or
the lookup can't be done. The lookup cannot be done for keys like the F1-F12 keys or the cursor keys, and
some drivers will only return approximate values. Generally, if you want to display the name of a key to
the user, you should use the scancode_to_name function.
Example:
int ascii;
...
ascii = scancode_to_ascii(scancode);
allegro_message("You pressed '%c'\n", ascii);