Migrate InputService from ImageJ

See:
* https://github.com/imagej/imagej-common/blob/imagej-common-0.2.0/src/main/java/net/imagej/display/InputService.java
* https://github.com/imagej/imagej-common/blob/imagej-common-0.2.0/src/main/java/net/imagej/display/DefaultInputService.java