Support clicks with key modifiers.

[Th3S4mur41]

Fixed merge conflicts from #356

[oktapodia]

Thank you for the PR, I would like to keep the backward compatibility for the version 0.6 if you don't mind

[Th3S4mur41]

@oktapodia What does that mean for the PR... Will it be merged in the next minor version or should I look to adapt it to be backwards compatible?
In the second case, could you point me to the incompatibility issues?

[FrankFlitton]

Any news about this? I'd like to shift+click in a project that I'm working on. The following code doesn't seem to work with the project's current codebase "out of the box".

robot.keyToggle("shift", "down");
robot.moveMouseSmooth(20, 20);
robot.mouseClick();
robot.keyToggle("shift", "up");