Add examples
new file:   ch24/item08/ColorDemo.java
new file:   ch24/item09/XOR.java
new file:   ch24/item10/FontInfo.java
new file:   ch24/item10/SampleFonts.java
new file:   ch24/item10/SampleFonts2.java
new file:   ch24/item10/ShowFonts.java
new file:   ch24/item11/CenterText.java
new file:   ch24/item11/MultiLine.java
new file:   ch24/item11/TextLayout.java