Added ability to display images to frame (v0.2.0.0)

- Software at v0.2.0.0.
- Added the files 'placeholder.png' and 'pokeball.png'.
- Added the private function 'displayImageFromFile' which attaches and
displays the specified file to the visible frame.
- Added an icon to the window ('pokeball.png').
- Added a placeholder image to test the display functionality
('placeholder.png').
- Stopped the window from being resizeable.
Added the file ignore list ('.gitignore')