Optimise ImageSequenceImporter.GetImageDimensions

[mlavik1]

See #52
Regarding this function:

UnityVolumeRendering/Assets/Scripts/Importing/ImageSequenceImporter.cs

Line 93 in 76dcfc6

private Vector2Int GetImageDimensions(string path)

ImageSequenceImporter.GetImageDimensions imports the whole texture just to get the dimensions. We should either find a faster way to check the dimensions (reading header only?), or at least make sure that we only read the images once during import (ideally async, but that should be another task).

[vahpy]

Minor changes fix this issue. I made in the commit vahpy@c45f374

[mlavik1]

Thank you! I will take a look at it :)