Updated mandatory question checking to ensure that on multi type questions (Arrays and Ranking type) all sections are completed before survey can be continued. Added hidden $_POST variable "lasttype" so that we can tell what the last question type was. Modified group description display, and welcome text display so that they are encapsulated in an invisible table centered and 80% of full width. This should make the welcome message and group descriptions look a bit neater.

git-svn-id: file:///Users/Shitiz/Downloads/lssvn/trunk/unstable@236 b72ed6b6-b9f8-46b5-92b4-906544132732