Demo: add responsive layout

[DJ-Raven]

This PR add responsive layout to demo project.

Example

// create jpanel
JPanel panel = new JPanel();

// set item size (-1 for use component preferred size)
Dimension itemSize = new Dimension(-1, -1);

// create responsive layout and set to jpanel
panel.setLayout(new ResponsiveLayout(ResponsiveLayout.JustifyContent.FIT_CONTENT, itemSize));

// add component to panel
panel.add(component);

Full responsive layout constructor

ResponsiveLayout(JustifyContent justifyContent, Dimension size, int horizontalGap, int verticalGap, int column)

Justify content

public enum JustifyContent {
    START, END, CENTER, SPACE_BETWEEN, SPACE_AROUND, SPACE_EVENLY, FIT_CONTENT
}

Demo form