Update topics/about_control_structures.js

Line 70: "null coallescion" -> "null coalescing"
Update topics/about_functions_and_closure.js

Line 45: "add 1,2,3,4,5" -> add 4,7,-2"
Merge pull request #19 from jayturley/patch-1

Update topics/about_control_structures.js
Merge pull request #20 from jayturley/patch-2

Update topics/about_functions_and_closure.js
Trivial spelling corrections
Clarify prototype chain tests
Make the comments match the variable names in prototype chaining
Trivial fixing of comments
Clarified 'this' koans
Changed the way innerVariable is shown to be undefined. try/catch hasn't been introduced yet, but testing the type has already been demonstrated previously.
Merge pull request #21 from SaintGimp/master

Fixes and clarifications from a newbie
Fixed qunit link
Update topics/about_scope.js

The answer was given,was that on purpose?
Merge pull request #25 from magopian/patch-3

Update topics/about_scope.js
fixed a problem in the hasOwnProperty test
Update README.md