console.lua: improved the hovered item calculation

Currently determine_hovered_item() assumes that each item is
opts.font_size pixels tall, which usually works well. This breaks with
fonts that get drawn taller than that, such as Japanese text, which
makes the calculation inaccurate for the top items and clips the
counter. A couple of users reported that it is inaccurate for them for
the top items even with ASCII characters, though I can't reproduce it.

To fix this place each selectable item in its own ASS event positioned
like determine_hovered_item() expects.

player/lua/console.lua

@@ -602,8 +602,16 @@ local function update()
     local log_ass = ''
     local log_buffer = log_buffers[id]
     for i = #log_buffer - math.min(max_lines, #log_buffer) + 1, #log_buffer do
-        log_ass = log_ass .. style .. log_buffer[i].style ..
-                  ass_escape(log_buffer[i].text) .. '\\N'
+        local log_item = style .. log_buffer[i].style .. ass_escape(log_buffer[i].text)
+
+        if selectable_items then
+            ass:new_event()
+            ass:an(1)
+            ass:pos(x, y - 1.5 * opts.font_size - (#log_buffer - i) * opts.font_size)
+            ass:append(log_item)
+        else
+            log_ass = log_ass .. log_item .. '\\N'
+        end
     end
 
     ass:new_event()