Custom tracks support

[Faraphel]

The mod will now try to propose his own system of custom tracks management to be more independent and avoid some limitation and default values fixed by LE-CODE.

(NOTE : I thanks the mkw-sp team and the mario kart wii decompilation project for their incredible work on the game that helped me understand the mechanisms behind the game)

• Load track by numeric id
• Change menus to allow more cup
• Load text from bmg file
• Allow the track to have custom "special" slot values

[Faraphel]

The first part of this issue is to change the way track are loaded.
On a PAL game, most of the operation to change are done around the function at 0x80540760 that load a track from its id.

at 0x80540820, we can find an assembly function that translate to :

snprintf(courseName, 0x80, "Race/Course/%s_d", COURSE_NAMES[courseId]);

The goal is to replace it with an equivalent to :

snprintf(courseName, 0x80, "Race/Course/%04x_d", courseId);

Which would then allow loading the track only by its id and would technically allow up to 0x10000 = 65536 tracks slots.