should be spilled. Add a simple mechanic to stop possible infinite loop
in regalloc.

-> Made API and tests use `transmute` for f64/u64 instead of `as`
-> Changed relevant logical shifts to (correctly) be arithmetic shifts
-> Fixed small typo in tests
-> (misc) Made STORE correctly handle arbitrary (< 64) sized ints

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.

Fixed a bug when passing 128-bit integers on the stack. Also added a diagnostic message of the entry function returns.

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.