Added JavaScript equivalents of many more PHP functions in ExpressionManager (from phpjs.org). To keep codebase small, only added functions expected to be needed.
Added many more test cases, especially of strings that contain special characters
Still trying to find right balance of use of addslashes() and htmlspecialchars() in Javascript generation (e.g. surveys run properly, but some unit tests still fail).

git-svn-id: file:///Users/Shitiz/Downloads/lssvn/source/limesurvey_ci@10862 b72ed6b6-b9f8-46b5-92b4-906544132732