Set symtable's in_func before parsing
typedef checks back in, now where they should be
If we find a decl without a symbol it's an error

symtab_search() may find something but return NULL which was causing
false errors.
typedef-types are now handled in the type tree
Move argument-into-scope addition to the parse stage
__builtin_va_list creations takes a symtable for tdef folding
Fold decls before parsing a statement block

i.e. add and create symbols for them, for identifier lookup
Put dereference-error-check back in
Move if-stmt parsing into the flow-parsing group
Fold expressions once we know their decay status
Reorder decl-parsing and adding to scope, for recursion
Fixed parsing of nameless sub-structs/unions
Fixed parsing of comma after nameless decl