Added a post on the physics gun/direct manipulator

Signed-off-by: Martin Evans <martindevans@gmail.com>
Fixed the tagline

Signed-off-by: Martin Evans <martindevans@gmail.com>
Update _posts/2013-01-22-Mathematical-Trickery.md
Merge pull request #10 from Drelnoch/patch-9

Update _posts/2013-01-22-Mathematical-Trickery.md
Merge branch 'To_Be_Proof_Read'