Break out of loop once the duplicate content found 

Fixes #328.

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

10x faster with many blocked IPs

Store phrases in one variable, return as soon as possible. This results in extra includes in some circumstances but overall it's still faster.

it is not required to loop through the other posts once the matched post
found

Fixes #315.