Add continuous scrolling to line cursor mode

Add continuous scrolling to line cursor mode

Do not move cursor if more lines do not exist (yet)

Revert "Do not move cursor if more lines do not exist (yet)"

This reverts commit 7539274.

Does not allow you to scroll to end of message.

lib/sup/modes/line_cursor_mode.rb

@@ -94,9 +94,16 @@ def cursor_down
     call_load_more_callbacks buffer.content_height if @curpos >= lines - [buffer.content_height/2,1].max
     return false unless @curpos < lines - 1
 
-    if @curpos >= botline - 1
-      page_down
-      set_cursor_pos topline
+    if @curpos == botline - 3
+      # load more lines, one at a time.
+      jump_to_line topline + 1
+      @curpos += 1
+      unless buffer.dirty?
+        draw_line @curpos - 1
+        draw_line @curpos
+        set_status
+        buffer.commit
+      end
     else
       @curpos += 1
       unless buffer.dirty?
@@ -111,10 +118,15 @@ def cursor_down
 
   def cursor_up
     return false unless @curpos > @cursor_top
-    if @curpos == topline
-      old_topline = topline
-      page_up
-      set_cursor_pos [old_topline - 1, topline].max
+    if @curpos == topline + 3
+      jump_to_line topline - 1
+      @curpos -= 1
+      unless buffer.dirty?
+        draw_line @curpos + 1
+        draw_line @curpos
+        set_status
+        buffer.commit
+      end
     else
       @curpos -= 1
       unless buffer.dirty?