Fix for Bug #1252139 : Send Task via Email plugin - Add a button to the main window toolbar to send email

Fix for bug #1252139 : Send Task via Email plugin - Add a button to the main window toolbar to send tasks as email from Main window.

Added a button in main window, enabling users to send tasks as email from main window.
Can you create a function that constructs a button? If somebody changes one button, it should change the other on e as well