deleted some files

        Changes to be committed:
	deleted:    demo.txt
	deleted:    demo_copy.txt
	deleted:    javaBiBasic/src/javaBiBasic/Day19/IoBufferWriter.java
LineNumberReader

        Changes to be committed:
	new file:   demo.txt
	new file:   demo_copy.txt
	modified:   javaBiBasic/src/javaBiBasic/Day19/BufferedReaderTest.java
	new file:   javaBiBasic/src/javaBiBasic/Day19/LineNumberReaderDemo.java