v0.1 Simple text console on screen works

Features for v0.1:

Simple text console printing output of a forked process on the screen. This console is implemented
in 64bit userspace and uses the fork(), pipe(), open(), close(), dup2(), read() and write() system
as well as a modified version of the musl libc. Of course, you can also have a console on one of the
serial port. Consoles and the started init binary is configurable on the kernel command line.

No filesystem support, yet. The userspace can only be passed as a module by the bootloader.