GUI Redesign
 - Redesigned GUI so that data enrty fields are on the right of the site selection toggle buttons. closes #21
 - All elements now have fixed widths - the window will auto-size to contain all of the controls within it. closes #22.
 - Added Scroll bar to optionGroup. Scroll is set in main GUIOptionGroup class. closes #23
 - Selecting a launch site now causes the input controls to contain the relevant launch site  parameters. Also added a Clear button to clear the contents of the input controls. closes #27