Replace it with two functions that won't run into issues with
trying to call bound objects, instances, etc. that weren't on
the stack. In general, if you have a callable value of unknown
type you should call `krk_callStack` with it on the stack followed
by all of its args; to make this abundantly clear, `krk_callStack`
only takes the argument count. For calling things we know to be
safe (closures and natives), there is `krk_callDirect`, which should
be used, for example, when calling core methods like __repr__.
- Don't clear the HAS_EXCEPTION bit.
- Reuse CLEAN_OUTPUT to disable printing the exception.
- Don't reset the stack, repls should do that _on every call_.
- Fix up sandbox and simple-repl.h, they don't need to do that silly stack thing to handle exceptions themselves.
