Expose createArrayFromView and getAxisOffsets

[PeterC-DLS]

1. @h5web/lib does not handle views of ndarray so can end up using the wrong portion of the underlying 1D typed array and passing it to WebGL. Exposing createArrayFromView allows devs to handle this case.
2. The space left when displaying images, etc is a problem when a dev wants to pack in several plots close together in an UI. Exposing getAxisOffsets allows them to control the aspect ratio and match the length of the scale axes to the image.

[axelboc]

I've pushed a commit to document createArrayFromView and move getAxisOffsets to the experimental section: b35a934

Could you please expand on the second problem you're facing (packing several plots close together)? Maybe we can find a solution to save you from implementing what seems like a complicated workaround.

[PeterC-DLS]

Thanks for the quick merge!

Please see DiamondLightSource/davidia#226 for the change we added so page resizes do not add padding to a RgbVis - this is demonstrated here.

[axelboc]

I see, thanks a lot. This was the initial equal-sizing behaviour right at the start but we ended up removing it to avoid the container measuring step and because we wanted to maximise the space available to the visualization when zooming in.

I considered bringing this sizing behaviour back, but looking at DiamondLightSource/davidia#226, your toolbar complicates things a bit. Let's keep the getAxisOffsets export then. I'll document it. EDIT: done in 079c700