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.

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.

bytecode: Increment stack to compensate for dispatch return value

lang: Remove OP_DROP since we clean up when returning anyway

lang: Add function calls to bytecode

lang: Change OP_RET to 0x03 ...

In order to make embedding ASCII in to the bytecode for method calls
easier we're going to reserve all ASCII values and NULL as NOPs.

lang: Add OP_DROP to bytecode

lang: Implement basic bytecode for returning values