Run completion tasks after updating result pane

The speed submitted via OnePixel log and the speed reported in
the tooltip is the speed calculated after typing the last but
one character of a lesson. The speed calculated after typing the
last character is displayed only in the result pane. This is
neither submitted via OnePixel log nor displayed in the tooltip.
This issue occurs because the log is submitted and the tooltip
is updated before the speed and error are computed after each
key press. Fix this issue by submitting the log and updating the
tooltip after the speed and error are computed after each key
press.
Display time taken in the speed tooltip

Display the time taken and the number of characters typed in the
speed tooltip in the result pane.
Display typing duration to 3 decimal places only

The speed tooltip displays the duration of typing. When the
duration is 29827 milliseconds, it is displayed as
29.826999999999998 seconds in the tooltip. Display 29.827
seconds instead by running this value through the JavaScript
toFixed function.
Add yet more usage of 5 and 8 in Unit 17.1

Add more instances of '5' and '8' to Unit 17.1, so that the user
gets more revision for the characters learnt in Unit 16.