Hdf5Viewer modifications

[grisaitis]

• If datasets have >4 dimensions, try to reshape them (e.g. if they have a leading (1,) axis)
• Fix units of offset parameter for self.add to be in nanometers, not voxels (before, after)
• Distinguish between file path and file name
  • and use just the file name, not the full path, for naming neuroglancer layers

[grisaitis]

https://github.com/funkey/nyroglancer/commit/140e9e9d4750b82d2465150d7679f6eeba875a4e changes behavior in that the names of layers aren't the full file path, but rather just the filename and the hdf5 dataset address. without that commit, you can have huge layer names that make it impossible to see any other ones.