gracefully handle crashes of a user mode programm

fix interrupts occuring while in user mode

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

use string identifiers for events ...

(some rework of the string saving system was required)

mov syscall handlers to different files

add a static libary and fix interrupts

print a message when a key is pressed

enable subscribing to an interrupt and set up the PIC

end tasks when they trigger an exception

enable interrupts