Add scroll left/right support

README.asciidoc

@@ -161,6 +161,8 @@ view.
  * _vb_: scroll to put the main selection on the bottom line of the window
  * _vj_: scroll the window count line downward
  * _vk_: scroll the window count line upward
+ * _vh_: scroll the window count columns left
+ * _vl_: scroll the window count columns right
 
 Multi Selection
 ---------------

src/normal.cc

@@ -194,6 +194,12 @@ void view_commands(Context& context)
         case 'k':
             context.window().scroll(-std::max<LineCount>(1, context.numeric_param()));
             break;
+        case 'l':
+            context.window().scroll( std::max<CharCount>(1, context.numeric_param()));
+            break;
+        case 'h':
+            context.window().scroll(-std::max<CharCount>(1, context.numeric_param()));
+            break;
         }
     });
 }

src/window.cc

@@ -57,6 +57,11 @@ void Window::scroll(LineCount offset)
     m_position.line = std::max(0_line, m_position.line + offset);
 }
 
+void Window::scroll(CharCount offset)
+{
+    m_position.column = std::max(0_char, m_position.column + offset);
+}
+
 void Window::update_display_buffer()
 {
     scroll_to_keep_cursor_visible_ifn();

src/window.hh

@@ -35,6 +35,7 @@ public:
     void center_selection();
     void display_selection_at(LineCount line);
     void scroll(LineCount offset);
+    void scroll(CharCount offset);
     void update_display_buffer();
 
     DisplayCoord display_position(const BufferCoord& coord);