Small improvement in handling of the input
Fix bug with backspace handling
Add some safety
Protect kalloc
Add a way to get RFLAGS register value
Interrupt handling

Intel interrupt gates are automatically disabling the interrupts.
So it is not necessary to disable them on IRQs and ISRs, but it is
necessary to enable them in system calls
Clean
Remove timer::sleep_ms

This function was unsafe with interrupts. Interrupts were enabled
and disabled with no regards to previous value. It was a bug, but
it was making ATA working better...