优化，完善注释，可生成javadoc

优化注释
	modified:   bin/com/lj/test/TestCachedThreadPool.class
	modified:   src/com/lj/util/ParallelComputing.java
	modified:   src/com/lj/util/ParallelComputingProcess.java
	modified:   src/com/lj/util/ParallelComputingProcessImpl.java