bump version to 0.5.0
[README] update for 0.5.0
[win] fix that setAlwaysOnTop doesn't work when application isn't focused

  fix #655
Merge pull request #657 from owenc4a4/i655

[win] fix that setAlwaysOnTop doesn't work when application isn't focuse...
Merge pull request #658 from owenc4a4/test

[Test] fix bug of some test, add test case for #655