lang: Switch to callee cleanup of non-return arguments ...

This simplifies calling things and will allow proper tail calls.

lang: Create vm state once in main

lang: Add back reference counting ...

The basic idea here is that we transfer ownership to and form the stack,
and clean up references that way.

lang: Clarify what skipping over ASCII and unknown OPs means

vm: Add stack pushing and popping

lang: Use vm_stack_get and set for OP_GET and OP_SET

lang: Rename vm.stack to vm.stack_next

lang: Add stack bases to vm

lang: Remove checks for obj->class_data ...

I have no idea how these could even trigger.

lang: Drop reference counting, embrace leaking ...

I will add proper garbage collection later

lang: Wrap stack functions

number: Don't check if return is NULL ...

This doesn't really matter since we will overwrite it

lang: Replace args with a vm_state stack ...

This doesn't have any functional changes at the moment but will
aid in adding proper stack support in the future.

lang: Fix Return register being wrong

lang: Check for undefined variables

lang: Compile to bytecode and run

lang: Add Minus operation for numbers

lang: Handle compiler register allocation

lang: Add compiler IR

lang: Finish very simple parser

lang: Add the beginnings of a bootstrap compiler

lang: Remove misleading comment

bytecode: Garbage collect the stack ...

This treats the stack itself as a place of references that needs to
be garbage collected and cleaned up. This will allow tail calls later.

object: Abort if objptr is NULL

lang: Add arg count to OP_CALL

lang: Pass arg_count to bytecode_run to aid stack allocation

lang: Fix arg counts to include return value

lang: Add stack get and set operations ...

This allows us to duplicate values and re-use them.

lang: Pass NULL values to calls first instead of later ...

This looks a bit awful right now but will be important later on
when we add proper support for calls in bytecode.

lang: Don't abort if there's been a double free ...

This is actually a use after free!