Adapt to java11 & use maven & add some functions
Changes:
- add function 'Hole', for skillful usage
- add function 'Length', for getting string's length
- 'com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel' was removed in new jdk version, so make it compatible
- convert to maven project
- move packages to 'com.github.trytocatch'
It's still compatible with jdk6