Move Lesson 10 to isKeyPressed

Lesson 10 now uses isKeyPressed for keyboard event handling.

Also moved to switch/case for other keyboard event handling,
rather than sequentially chained 'if' statements.
A little tidying on lesson 11

Moving to switch/case for keyboard event handling,
rather than sequentially chained 'if' statements.

Minor changes to lessons 7, 8, 10.