exception : made some major improvements

[abdelali221]

1 - It's now possible to see the last frame rendered by the software.

2 - The way the exception details are displayed was changed, it's more tight now.

3 - Changed control mapping.

4 - Changed how the controls are shown to the user.

5 - Fixed a bug with the GameCube controller not working if PAD_Init() wasn't called by the software (thanks to DacoTaco who pointed the potential issue).

Edit : The last frame thing is only available if the app compiled sets the framebuffer lookup address, if not, the text "Start : Show last XFB" won't appear.