[libsigcplusplus] slot_list: Remove this now-unused class.

[Murray Cumming <murrayc src gnome org>]

commit fb57d3ff2d5b83e2e701e5bd8f6904ff28d4d0be
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Apr 21 14:05:56 2016 +0200

    slot_list: Remove this now-unused class.

 sigc++/signal.h |   78 -------------------------------------------------------
 1 files changed, 0 insertions(+), 78 deletions(-)
---
diff --git a/sigc++/signal.h b/sigc++/signal.h
index fd2a44e..d7280c7 100644
--- a/sigc++/signal.h
+++ b/sigc++/signal.h
@@ -92,84 +92,6 @@ struct slot_iterator
   iterator_type i_;
 };
 
-/** STL-style list interface for sigc::signal#.
- * slot_list can be used to iterate over the list of slots that
- * is managed by a signal. Slots can be added or removed from
- * the list while existing iterators stay valid.
- *
- * @ingroup signal
- */
-template <typename T_slot>
-struct slot_list
-{
-  using slot_type = T_slot;
-
-  using reference = slot_type&;
-  using const_reference = const slot_type&;
-
-  using iterator = slot_iterator<slot_type>;
-
-  using reverse_iterator = std::reverse_iterator<iterator>;
-
-  slot_list() : sig_impl_(nullptr) {}
-
-  explicit slot_list(internal::signal_impl* sig_impl) : sig_impl_(sig_impl) {}
-
-  iterator begin() { return iterator(sig_impl_->slots_.begin()); }
-
-  iterator end() { return iterator(sig_impl_->slots_.end()); }
-
-  reverse_iterator rbegin() { return reverse_iterator(end()); }
-
-  reverse_iterator rend() { return reverse_iterator(begin()); }
-
-  reference front() { return *begin(); }
-
-  const_reference front() const { return *begin(); }
-
-  reference back() { return *(--end()); }
-
-  const_reference back() const { return *(--end()); }
-
-  iterator insert(iterator i, const slot_type& slot_)
-  {
-    return iterator(sig_impl_->insert(i.i_, slot_));
-  }
-
-  iterator insert(iterator i, slot_type&& slot_)
-  {
-    return iterator(sig_impl_->insert(i.i_, std::move(slot_)));
-  }
-
-  void push_front(const slot_type& c) { insert(begin(), c); }
-
-  void push_front(slot_type&& c) { insert(begin(), std::move(c)); }
-
-  void push_back(const slot_type& c) { insert(end(), c); }
-
-  void push_back(slot_type&& c) { insert(end(), std::move(c)); }
-
-  iterator erase(iterator i) { return iterator(sig_impl_->erase(i.i_)); }
-
-  iterator erase(iterator first_, iterator last_)
-  {
-    while (first_ != last_)
-      first_ = erase(first_);
-    return last_;
-  }
-
-  void pop_front() { erase(begin()); }
-
-  void pop_back()
-  {
-    auto tmp_ = end();
-    erase(--tmp_);
-  }
-
-private:
-  internal::signal_impl* sig_impl_;
-};
-
 namespace internal
 {