Provide equivalent to BdvFunctions.show()

[kephale]

The function https://github.com/bigdataviewer/bigdataviewer-vistools/blob/ad25cea0edcc8c5e971ef92fed0d2d9f75fc9242/src/main/java/bdv/util/BdvFunctions.java#L86

is used heavily in ImgLib2-based projects and scripts for quickly displaying an images. Having a function like SciView.show() would make it very easy to test whether sciview can work in those situations.

[kephale]

Note that there are some BvvFunctions now: https://github.com/bigdataviewer/bigvolumeviewer-core/blob/master/src/main/java/bvv/vistools/BvvFunctions.java. We want almost identical function signatures, but to use SciViews instead of BDVHandles