refactor syscall.c

fix issue vga driver: newline doesn't move cursor #2

use sleep function for xhci driver waiting for the controller to start

add sleep function to PIT driver

add system time readout

add basic PIT timer outline

receive xhci events

try initializing xhci hub

fix issue #1: ELF files not loaded correctly

print out xhci port info

refactor usb driver to use an internal memory structure

allocate scratchpad buffers whenever implemented

add system call to retrieve the physical location of a virutal address

initialize XHCI controller and correctly list anvailable slots

add screenshot to README

add screenshot

print basic XHCI information

add scanning for usb devices

precache pci devices

add lspci user programm

prevent bad behaviour when loading a service that has already been loaded

move 'gets'-functionality to ioManager to simplify the shell source code

add await syscall

update the cursor position in the vga driver

start the program name entered in the shell

add input buffering for the shell

check if a message should be printed to the main vga screen by checking if any syscall in the 'syscall stack' is the foreground process

pass keyboard input to shell

remove old log function, make \n mandatory for printing a new line

route the shell service to the vga output