Replaced reserved ifdef guards
Fixed where-positioning after parsing numbers
Fixed parsing of parenthesised functions [int((*p)(void))]
Removed -fms-extensions default
Changed notion of struct/union completeness - needs layout

structs/unions are now complete once they've been laid-out, not when
they have all their decls
struct/union/enum folding in 3 stages

This allows for completeness checking but prevention of infinite
recursion while folding sub-members of the same s/u/e
Always treat untagged-structs as a C11 extension

We warn in C89/C99 mode. Tagged structs are still an error, unless
-fms/plan9-extensions
General test fixes
Removed test2/lib/
Initialisation fixes (partial, more next)
symtab_fold_decls() cleanup
symtab_fold_decls() recursively descends on symtables
Warn on function pointer arithmetic
Finer grained detection of duplicate local definitions
Stricter _Generic() checks
_Generic tests - new and old/moved
Added cpp2 bug with paren handling