Design main UI window

Design input methods for UI frontend
Finish FIrst UI part
Add File Opening logic
Add a worker class

This class does all the calculations needed to show the average of the
numbers to the user
Add error-cheking to FileIO
Make some buttons functional

Partial logic for button work coded.
Add more controls to UI
Enable reset button
Remove deprecated function

reset() was never needed in a class that gets instanced everytime it is
needed.
Remove legacy code

Console version of the program eliminated
Change error message

A more user friendly message has been written
Add an About dialog

A new dialog has been made, it shows information about the app, including its name, the version and the copyrigth.
Start fixing memory leak

There is a small memory leak that should not happen. GC can resolve it, but a more efficient method must be found.
Add a program icon and publish options
Refine app presentation and icon placement.
Merge pull request #1 from rlam1/UI_Frontend

Ui frontend