Test add
more add and sub tests
remove per-unit variable integer size, integers are now always 64-bit
implement std::hash for value_type::object
test mul, div
test mod, and, or, xor
interpreter stores a pointer to the currently executed function in local 0; test shift and recursion
use a locals vector per interpreter, not per call
simplify call instruction
fix some instructions using get; make recursion test do something