fix issue #3: crash when running an unknown program

refactor syscall.c

route the shell service to the vga output

add basic stack tracing ability

rename service proivder to service function ...

now matches the documentation in the wiki

add kernel events ...

kernel events get triggered by the kernel when certain things happen.
first example: log a message whenever a new programm is loaded from the initrd

add an additional argument to request calls

make malloc functions accessible to user mode programs

mov syscall handlers to different files

add a static libary and fix interrupts

minor code cleanup regarding loading ELF files and running the main function

enable subscribing to an interrupt and set up the PIC

end tasks when they trigger an exception

enable interrupts

enable freeing of memory

add passing data to a syscall

use registers for passing data to system calls

add the ability to create multiple services and repair inter-service communication

add port IO syscalls

clean up syscall code

add basic cross-calling of service providers

organize services and their providers

enter usermode for user processes and start with some memory protection

first steps in services that can be run by the os

read elf data into a new page table

read the initrd file to get the memory location of the first userspace program

find the initrd in the multiboot 2 information structure

add basic kernel page management

initial commit