%smoke-stack-set-int-pointer!: a comment
smoke-stack-populate!: error report actual stack sizes

..including item 0, used for return values
instantiate: correction concerning required stack size
smoke-stack-getters, smoke-stack-setters: use hash table

Libraries that use smoke-egg may want to add new types to these structures,
so it makes more sense to use hash tables.
smoke-stack c-string support
smoke-stack-add-type!: add new types to smoke-stack-{getters,setters}