Centralize the execution of statements and evaluation of expressions
so that the user can specify a debugging "callback" after every
execution/evaluation.
The callback can be used for myriad things, but it seems likely that
it will be useful for implementing:
1. Testing
2. Debugger
Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
When a function is called, if there is an (in)out parameter,
make sure that updated values are propogated to the calling
function.
Signed-off-by: Will Hawkins <hawkinsw@obs.cr>