Putting on basic GUI and ressources

Cleaning MainActivity.java
Creating GUI components in fragment_main.xml
Creating labels and titles strings in strings.xml
Completing basic GUI

Setting ID to the panels (menu and preview)
Adding a colour radio group to the menu panel
Adding strings for the colours of the radio group
Adding colours

Adding colours.xml, and a few values for the colours
Adding styles and drawables

Creating styles for the buttons and the background
Adding drawables (9-patches) for the buttons
Setting GUI (to correct and finish)

Creating a default drawable folder and moving drawable files in it
Creation of a custom layout, Slider
Fixing GUI by implementing Slider