Add and fix copyright notices for better GPL compliance (thanks @naehrwert and @CTCaer).

fusee: Complete re-write of the hardware initialization code: ...

- Updated code to match hekate's;
- Improved nxboot (now boots firmwares 2.x successfully);
- Temporarily disabled built-in boot system module support;
- Fixed multiple bugs.

Redesign fs_dev, raw_dev, introducing device_partition and switch_fs. ...

In theory, one could mount an encrypted FAT partition itself coming from a disk image, etc.

Rewrote crt0, init, and chainloading code ...

start.s, init.c, linker.ld and linker.specs are meant
to be re-used by user applications, should they remove the defines
from init.c and the .chainloader* sections from the linker script

fusee: update header names for starting cpu0

Change fusee folder naming