* expand() will only touch the memory once
* fixed missing if-else cascade at toy_routine.c:90
* unary negate will not optimise numbers unless the '-' character is immediately prior
* fixed broken test for unary negation of groups
The parser now correctly produces a workable AST. I think I'll skip
over the optimizer, and begin on the compiler next session. The
optimizer will act directly on the AST, but it isn't totally necessary.
Other tools can also operate on the AST, such as for debugging - I'll
have to ask what kinds are out there.
