Filtered due to lack of support in MySQL < 5.5.3.

do not allow user to post the duplicate question once more time . It
checks the last 5 questions and compares with the current one . If any
of them appears to be same the user will be warned and the question will
not be posted
Fixes - #309

Set to Unix line endings in repo; the gitattributes file means they
will be converted to suit the user’s system.