add Errbox
add errobox
add 半透明层以及色盘的隐藏。
颜色调整调用以及
Merge http://github.com/android-fucking/drawing-board

Conflicts:
	projects/DrawingBoard/drawingboard/src/main/java/cn/edu/shu/android/drawingboard/Errorbox.java
	projects/DrawingBoard/drawingboard/src/main/java/cn/edu/shu/android/drawingboard/MainActivity.java
	projects/DrawingBoard/drawingboard/src/main/res/layout/activity_main.xml