Prioritized using caller saved registers over callee saved registers, fixed bug when passing constant int<128> to functions, improved saving of XR and elimited all warnings in the aarch64 backend.

Also modified some of the rust tests so that they are applicable to aarch64.

Added support for generation of unscaled immediate memory offsets.
Fixed compilation errors.
Modified calling of the c 'exit' function in tests so that it will expect a int<64> instead of an int<32>.
Modified formating of various IR things (like Value's and Instructions) to be more easillly readable.

macro.

immiediate number. Richards benchmark runs.

stack pointer before calling, unless we pushed arguments by stack)

still restored callee-saved registers, should directly jump to it

[wip] let backend know about exception flow. also add one more test to see if callee-saved register is restored
during catching exception, the test failed (and I marked it as ignored).

liveins

(for calling convention)

No regression, but new tests still doesn't run. Marked them
as expect fail or skip. Going to work on them later.

need to be fixed)

results in different code (the same as clang did)