Added additional hotkeys for presentations compatible to other office suites 

in addition to previously add 'b' for blank out, add other hotkeys (w, dot, comma, Home, End) - as used in other office applications such as LibreOffice and OpenOffice: https://help.libreoffice.org/Impress/Shortcut_Keys_for_Impress

Refactored blankOut function for reuse. In addition, as per previous commit add the 'p' key for pink screen.