Strategy for allocating storage:

1. Allocate stack for variables which HAVE to have it.

2. Assign 'known' locations for variables at the end of branches.
	2a if the variable is in follow_vars, use that location
	2b if the variable is not then use goalinfo derived information
	ELSE use stack location ELSE panic

3. Assign inbetween locations for eager code generation:
	use 2a, 2b, allocate 'any' free register.