- Primitives can now signal an error.
- An error prints a callstack and ends the current (and right
now only) fiber.
- Arithmetic operators error if the operand is not a number.
- Real error for method not found.
- Associate source file name, and method names with functions.
- Debug line number info for functions.
Unfortunately, this regresses perf on fib about 15%, mostly
because of the better checking in arithmetic ops.
There's still a bunch of clean up to do, but this is a big step
in the right direction.
It used to subtract the number of bytes during deallocation, but
that required knowing the size of an object at free time. That
isn't always available. The old code could read a freed object
while doing this. Bad!
Instead, this tracks how much memory is still being used by
marked objects. It's correct, and is also a bit less code and
faster.
