WIP: Floats and sleep

This branch primarily pertains to the implementation of the syscalls for printing and reading floating point numbers. The syscalls for reading floating point numbers were previously unimplemented, whereas the ones for printing floating point numbers contained a bug that prevented the number infinity from being printed, and a bug that caused floating point numbers to overflow when the integer part of the number was greater than the maximum value of a 64 bit integer.

I also implement a function to set timer interrupts via the rtc and a syscall to sleep (i.e. wait for that interrupt).