Introduce more CTL content

This change introduces accumulate, addressof, advance, all_of, distance,
array, enable_if, allocator_traits, back_inserter, bad_alloc, is_signed,
any_of, copy, exception, fill, fill_n, is_same, is_same_v, out_of_range,
lexicographical_compare, is_integral, uninitialized_fill_n, is_unsigned,
numeric_limits, uninitialized_fill, iterator_traits, move_backward, min,
max, iterator_tag, move_iterator, reverse_iterator, uninitialized_move_n

This change experiments with rewriting the ctl::vector class to make the
CTL design more similar to the STL. So far it has not slowed things down
to have 42 #include lines rather than 2, since it's still almost nothing
compared to LLVM's code. In fact the closer we can flirt with being just
like libcxx, the better chance we might have of discovering exactly what
makes it so slow to compile. It would be an enormous discovery if we can
find one simple trick to solving the issue there instead.

This also fixes a bug in `ctl::string(const string &s)` when `s` is big.

ctl/back_inserter.h

@@ -0,0 +1,64 @@
+// -*-mode:c++;indent-tabs-mode:nil;c-basic-offset:4;tab-width:8;coding:utf-8-*-
+// vi: set et ft=cpp ts=4 sts=4 sw=4 fenc=utf-8 :vi
+#ifndef CTL_BACK_INSERTER_H_
+#define CTL_BACK_INSERTER_H_
+#include "iterator.h"
+#include "utility.h"
+
+namespace ctl {
+
+template<class Container>
+class back_insert_iterator
+{
+  protected:
+    Container* container;
+
+  public:
+    using iterator_category = ctl::output_iterator_tag;
+    using value_type = void;
+    using difference_type = void;
+    using pointer = void;
+    using reference = void;
+
+    explicit back_insert_iterator(Container& c) : container(&c)
+    {
+    }
+
+    back_insert_iterator& operator=(const typename Container::value_type& value)
+    {
+        container->push_back(value);
+        return *this;
+    }
+
+    back_insert_iterator& operator=(typename Container::value_type&& value)
+    {
+        container->push_back(ctl::move(value));
+        return *this;
+    }
+
+    back_insert_iterator& operator*()
+    {
+        return *this;
+    }
+
+    back_insert_iterator& operator++()
+    {
+        return *this;
+    }
+
+    back_insert_iterator operator++(int)
+    {
+        return *this;
+    }
+};
+
+template<class Container>
+back_insert_iterator<Container>
+back_inserter(Container& c)
+{
+    return back_insert_iterator<Container>(c);
+}
+
+} // namespace ctl
+
+#endif // CTL_BACK_INSERTER_H_