Allows doing some initialization based on the pid before starting a
process. For instance, a future commit will allow setting up the
stdin/out/err pipes before starting the process.

Twili, also known as the pipe manager (which is not pm), allows passing
stdin/stdout/stderr pipes to various sub-process. It is also responsible
for passing data around in the "dumb" pipes (basically unix pipes). It
has a generic interface, IPipe, that is implemented by those dumb pipes,
but also by vi Terminals and, eventually, fs Files.

When booting from UEFI, multiboot infos are a lot bigger for whatever
reason. They're so much bigger, they span multiple pages! As such,
bootstrap now accepts multiple pages for the multiboot. The kernel
already allows multi-page multiboot infos (it tells the frame allocator
to reserve the whole multiboot info region).

When disk initializer sees two conflicting files, it will now chose the
earliest file instead of panicking.

We should strive to keep the source directory clean, and only copy stuff
in the target/ directory. It keeps the gitignore simpler, and simplifies
a bunch of other things. So now we copy the binaries to
target/isofiles/boot instead.

Only run it on linux for now.