* Refactor entry point
* Remove unused code
* Reformat level header to be more clear, and add more comments
Looks like assembling with CMake will require some changes to the
assembler flags, and possibly some manual dependency specification.
We use the 6102 boot code by default, but this can be changed (for
example, if flashing to a cartridge with a different CIC).
As with the microcode, the path cannot be easily passed to the
linker script and so the hard-coded name should not be specific to
particular boot code.
Environment variable N64_ROOT optionally sets the root directory of
the N64 toolchain.
To enable this to work with the linker script, the microcode object
files are now copied to the build directory before linking (since
there is no easy way to pass the path to the script dynamically).
An added benefit to this approach is that different microcode can
now be used easily if desired.
