separate stack for kernel / user space

• introduce page guards to protect the stacks
• remove compiler warnings
• ensure CpuFrequency is never explicitly set to zero (PR #29)

add check if a task with higher priority is available

• wakeup handler checks if a task with higher priority is available
• if yes the handler calls the scheduler

completly revision of the scheduler

• lockless scheduling on a local core
• only the communication between cores is realized with protected cores
• cores use inter-processor-interrupts to trigger a queue check
• introduce a type to handle the CoreId => increase the readability of the code

remove deadlock during wakeup of an processor in halt state

• some code cleanups

add support of the latest memory allocator interface

• use AllocInit to check if a memory block has to be initialized

simplify PIC initialization

• remove compiler warnings

revision of IO-APCI handling, removing deadlocks

• remove deadlock if more the one cpu is activated
• revise IO-APIC handling for uhyve
• support of the latest version of the nightly compiler

add support of the latest nightly compiler

• add options to disable pci and acpi support
• remove bug in stack handling

use rust-lld as linker

• remove dependency from the old tool chain "x86_64-unknown-"
• switch to LLVM linker