Add support for .TIFF files

[SylviaWhittle]

We have had a request for .TIFF file format support. Initially we thought that this is nonsensical but apparently .tiff files can have metadata stored inside them, so we can access the pixel to nanometre scaling factor.

I'll update this issue when I find out more info

[derollins]

Just a thought on this, when opening TIFF files in other microscopy image analysis programmes then you can input a scaling factor manually. Would this is doable in topostats?

[SylviaWhittle]

@derollins It would be possible, though there would be much discussion and argument about how exactly this should be done.

One option could be to have a configuration parameter in topostats...

pixel_to_nm_scaling_factor: null # Manually specify the pixel to nanometre scaling factor. Will apply to ALL images that are processed, so all images MUST be the same resolution.