DEV: a liquid crystal display driver added

include/drv/liquid_crystal.h

@@ -58,6 +58,7 @@ namespace tbx {
      * \tparam Impl_t       The derived class
      * \tparam Lines        The lines of the LCD
      * \tparam Columns      The coluns of the LCD
+     * \tparam BusSize      The LCD bus size (4 or 8 bits)
      */
     template <typename Impl_t, size_t Lines, size_t Columns, size_t BusSize =4>
     class liquid_crystal : public Print<liquid_crystal<Impl_t, Lines, Columns, BusSize>, char>{
@@ -66,7 +67,8 @@ namespace tbx {
         static_assert((BusSize == 4) || (BusSize == 8), "BusSize must be either 4 or 8.");
 
     public:
-
+        constexpr static size_t lines   = Lines;
+        constexpr static size_t columns = Columns;
         /*!
          * Public enumerator to be used as argument to the init() function.
          * Selects the font size and thus the number of active lines
@@ -475,7 +477,7 @@ namespace tbx {
                     home ();
                     break;
                 case '\f':
-                    set_cursor (1, 1);
+                    clear();
                     break;
                 case '\b':
                     --cursor_;